CN210087590U

CN210087590U - Double-water-pump alternate start-stop control circuit

Info

Publication number: CN210087590U
Application number: CN201920823956.XU
Authority: CN
Inventors: 艾澜; 熊永俊; 王焕河; 段博; 郑庭华; 李子龙; 李杨松; 祁威威; 阚朝晖; 冯婧; 杜选一; 李玲
Original assignee: HUBEI BAILIANHE PUMPED STORAGE Co Ltd; State Grid Corp of China SGCC; State Grid Xinyuan Co Ltd
Current assignee: HUBEI BAILIANHE PUMPED STORAGE Co Ltd; State Grid Corp of China SGCC; State Grid Xinyuan Co Ltd
Priority date: 2019-06-03
Filing date: 2019-06-03
Publication date: 2020-02-18
Anticipated expiration: 2029-06-03

Abstract

The utility model provides a two water pump take turns to open and stop control circuit, including major loop and load control return circuit, the load control return circuit includes that manual opening is stopped the return circuit at least, open automatically and stop the return circuit, the fault switching return circuit, automatic switch signal return circuit, start the stop signal return circuit, control two pumps and move under manual mode and automatic mode, and when the overload situation appears, can know the fault situation directly perceivedly and make corresponding measure through the demonstration of overload lamp, take place with emergency, and convenient maintenance to the later stage. The utility model provides a two water pumps take turns to open and stop control circuit utilizes the logical relation of relay and auxiliary contact, realizes that two water pumps open according to the water level takes turns to automatic opening and stops, and this control circuit design benefit, simple and practical, low cost, it is convenient to maintain.

Description

Double-water-pump alternate start-stop control circuit

Technical Field

The utility model relates to a two water pump take turns to open and stop control circuit, this technique is applicable to various two water pump automatic control occasions.

Background

The automatic water pump starting and stopping device is applied to various production industries, and the automatic control circuit is utilized to automatically start the water pump to supplement water and drain water according to the water level condition. In practical application, two water pumps are generally designed, and can be started and stopped manually and automatically, when the two water pumps are started and stopped automatically, the two water pumps are started and stopped automatically and alternately according to the water level, one pump has a fault, and the other pump is started automatically.

At present, the control circuit for starting and stopping the double water pumps by turns generally adopts PLC control, and through PLC programming, functions of automatically starting and stopping the two water pumps by turns, switching faults and the like according to water level conditions can be very easily realized. Two water pump rotation start-stop control circuit based on PLC has following problem: the PLC has high price, the failure rate of a PLC module is high in humid and severe environments and the like, and the cost is high due to the fact that the module is replaced during later maintenance; and 2, the PLC application threshold is higher, technicians with certain professional ability are required for program editing and downloading in later maintenance, and ordinary maintenance personnel do not have maintenance ability.

Disclosure of Invention

An object of the utility model is to prior art not enough provide two water pumps and open and stop control circuit by turns, realize that two water pumps are automatic to open by turns and stop, control function such as failover, only used the relay, rotary switch, the thermorelay contact, electric components such as water level switch and overload indicator replace PLC control can the greatly reduced cost, electric components's fault rate is low simultaneously, later maintenance is also simpler than PLC, and can make corresponding measure through the observation to the overload lamp when the trouble transshipping, prevent emergency from taking place and convenient maintenance to the later stage.

The utility model adopts the technical proposal that: the double-water-pump alternate start-stop control circuit at least comprises a main loop and a load control loop, wherein two water pumps in the main loop are respectively connected with a thermal relay, a contactor and an air switch in series and then connected to an alternating current power supply in parallel; the load control loop at least comprises a manual start-stop loop, an automatic start-stop loop, a fault switching loop, an automatic switching signal loop, a start-stop signal loop and a power supply indicating loop; the manual start-stop loop at least comprises an operation branch; the operating branch is provided with two groups, namely a pump operating branch 1 and a pump operating branch 2, a contactor coil KM1 in the pump operating branch 1 is at least connected in parallel with an intermediate relay KA3 and then connected in series with a normally closed contact of a first intermediate relay and a normally closed contact of a first thermal relay, and a contactor coil KM2 in the pump operating branch 2 is at least connected in parallel with an intermediate relay KA4 and then connected in series with a normally closed contact of a second intermediate relay and a normally closed contact of a second thermal relay; no. 1 pump operation branch road is connected on zero line N with 2 pump operation branch road parallelly connected back one end and power fuse FU2 series connection after, the other end of No. 1 pump operation branch road is connected with the second pin of manual pump knob SA2 that opens, the other end of No. 2 pump operation branch road is connected with the third pin of manual pump knob SA2 that opens, the first pin of manual pump knob SA2 is connected on live wire L1 with manual automatic mode knob SA1 and power fuse FU1 series connection after, first auxiliary relay normally closed contact receives auxiliary relay KA4 control, and second auxiliary relay normally closed contact receives auxiliary relay KA3 control, the auxiliary circuit thermal relay is established to two sets of, is No. 1 pump thermal relay and No. 2 pump thermal relay respectively, and first thermal relay normally closed contact receives No. 1 pump thermal relay control, and second thermal relay normally closed contact receives No. 2 pump thermal relay control.

The automatic start-stop loop at least comprises an operation branch and an automatic branch, the automatic branch is provided with two groups, namely a pump automatic branch 1 and a pump automatic branch 2, a first intermediate relay normally-open contact and a signal intermediate relay normally-closed contact in the pump automatic branch 1 are connected in parallel and then connected in series with a first signal intermediate relay normally-open contact, and a second intermediate relay normally-open contact and a second signal intermediate relay normally-open contact in the pump automatic branch 2 are connected in parallel and then connected in series with a third signal intermediate relay normally-open contact; one end of the No. 1 pump automatic branch, which is connected with the No. 1 pump running branch in series, is connected with a third pin of a manual automatic mode knob SA1, and the other end of the No. 1 pump automatic branch is connected with a power fuse FU2 in series and then is connected with a zero line N; no. 2 pump automatic branch road and No. 2 pump operation branch road one end of establishing ties link to each other with manual automatic mode knob SA 1's third pin, connect on zero line N behind the other end series power fuse FU2, connect on live wire L1 behind manual automatic mode knob SA 1's the first pin series power fuse FU1, signal intermediate relay normally closed contact and first signal intermediate relay normally open contact receive signal intermediate relay KA1 control, first signal intermediate relay normally open contact and third signal intermediate relay normally open contact receive signal intermediate relay KA2 control, first intermediate relay normally open contact receives intermediate relay KA3 control, second intermediate relay normally open contact receives intermediate relay KA4 control.

The fault switching loop at least comprises an operation branch circuit, an automatic branch circuit and an overload branch circuit, wherein an overload indicator lamp HG1 in the No. 1 pump overload branch circuit is connected with an auxiliary contact of a first contactor in series, and an overload indicator lamp HG4 in the No. 2 pump overload branch circuit is connected with an auxiliary contact of a second contactor in series; a first pin of a manual-automatic mode knob SA1 is connected with a power fuse FU1 in series and then connected with a live wire L1, a second pin of the manual-automatic mode knob SA1 is connected with a first pin of a manual pump starting knob SA2, a third pin of the manual-automatic mode knob SA1 is connected with one end of a No. 1 pump automatic branch and one end of a No. 2 pump automatic branch, a second pin of a manual pump starting knob SA2 is connected with one end of a No. 1 pump overload branch, one end of a No. 1 pump running branch, the other end of the No. 1 pump automatic branch, one end of a first thermal relay normally-open contact and one end of a second thermal relay normally-open contact, a third pin of the manual pump starting knob SA2 is connected with one end of a No. 2 pump running branch, one end of a No. 2 pump overload branch, the other end of the No. 2 pump automatic branch, the other end of the first thermal relay normally-open contact and the other end of the second thermal relay normally-open contact, the other end of the No. 1, The other end of No. 2 pump operation branch roads and the other end of No. 2 pump overload branch roads are connected in power fuse FU 2's one end, and power fuse FU 2's the other end is even on zero line N, first contactor auxiliary contact receives contactor coil KM2 control, and second contactor auxiliary contact receives contactor coil KM1 control, main loop thermorelay establishes to two sets ofly, is No. 1 pump thermorelay and No. 2 pump thermorelay respectively, and first thermorelay normally closed contact receives No. 1 pump thermorelay control, and second thermorelay normally closed contact receives No. 2 pump thermorelay control.

In the automatic switching signal loop, after being connected in parallel, a fourth signal intermediate relay normally-open contact and a third intermediate relay normally-open contact are connected in series with a manual automatic mode knob SA1 and a power fuse FU1 in sequence and then connected on a live wire L1, and the other end is connected on a zero line N after being connected in series with a third intermediate relay normally-closed contact, a signal intermediate relay KA1 and a power fuse FU2 in sequence, wherein the fourth signal intermediate relay normally-open contact is controlled by the signal intermediate relay KA1, the third intermediate relay normally-open contact is controlled by the intermediate relay KA3, and the third intermediate relay normally-closed contact is controlled by the intermediate relay KA 4.

A water level switch signal K1 in the start-stop signal loop is connected in parallel with a normally open contact of a fifth signal intermediate relay, then is connected in series with a normally closed contact of a fourth signal intermediate relay and a signal intermediate relay KA2 in sequence, then is connected in series with one end of the water level switch signal K2 in series with one end of the signal intermediate relay KA5 in connection with a third pin of a manual-automatic mode knob SA1, a first pin of the manual-automatic mode knob SA1 is connected in series with a power fuse FU 25 and then is connected to a live wire L1, a water level switch signal K1 is connected in parallel with a normally open contact of the fifth signal intermediate relay, then is connected in series with a normally closed contact of the fourth signal intermediate relay and a signal intermediate relay KA2 in sequence, then is connected in series with the power fuse FU1 and then is connected to a zero line N, and the other end of the water level switch signal K; the normally open contact of the fifth signal intermediate relay is controlled by the signal intermediate relay KA2, and the normally closed contact of the fourth signal intermediate relay is controlled by the signal intermediate relay KA 5.

The power source indicating circuit at least comprises a power source indicating lamp HG5, one end of the power source indicating lamp HG5 is connected with the power fuse FU1 in series and then is connected onto the live wire L1, and the other end of the power source indicating lamp HG5 is connected with the power fuse FU2 in series and then is connected onto the zero line N.

Including pilot lamp HG2 in the branch circuit is operated to No. 1 pump at least, pilot lamp HG2 is parallelly connected back and is established ties with first intermediate relay normally closed contact and first thermal relay normally closed contact with contactor coil KM1 and intermediate relay KA3, include pilot lamp HG3 in the branch circuit is operated to No. 2 pump at least, pilot lamp HG3 is parallelly connected back and is established ties with second intermediate relay normally closed contact and second thermal relay normally closed contact with contactor coil KM2 and intermediate relay KA 4.

The utility model provides a two water pumps start-stop control circuit's beneficial effect lies in by turns: through the cooperation of the relay, the knob switch, the thermal relay contact, the water level switch and the overload indicator light, the circuit loop formed by electrical appliance components is used for controlling the functions of automatic alternate start-stop, fault switching, power indication and the like of the double water pumps, and whether the double pumps have overload faults or not can be intuitively known through the display of the overload light, and corresponding measures can be made in time to prevent the occurrence of emergency and facilitate the later maintenance, compared with the PLC control, meanwhile, the technical scheme provided by the utility model adopts a control circuit formed by an AC power supply, an air switch, an AC contactor, a thermal relay, a water pump, an AC relay, the knob switch, the thermal relay contact, the water level switch, the indicator light, the overload indicator light and a cable according to a specific connection mode, the main control part is realized through the relay, compared with the control scheme adopting the PLC, the cost is very low, because the relay is widely used in various control loops on the production field, the failure rate is lower, and the later maintenance is simpler than the PLC control.

Drawings

FIG. 1 is a main circuit;

FIG. 2 is a load control loop;

in the figure: 380V AC power supply 1, QF1 power air switch No. 1 pump No. 2, QF2 power supply switch No. 2 pump No. 3, KM1 contactor No. 1 pump No. 4, KM2 contactor No. 2 pump No. 5, FR1 thermal relay No. 1 pump No. 6, FR2 thermal relay No. 2 pump No. 7, No. 1 pump motor No. 8, No. 2 pump motor No. 9, FU1 control power fuse No. 10, SA1 manual automatic mode knob No. 11, SA2 manual pump starting knob No. 12, KM2-1 contactor auxiliary contact No. 2 pump No. 13, HG1 overload indicator No. 1 pump No. 14, HG2 operation indicator lamp No. 1 pump No. 15, KA3-4 operation relay No. 1 pump No. 16, KM 37-2 contactor coil No. 1 pump No. 17, KA4-1 operation relay No. 2 pump No. 18, FR1-1 thermal relay No. 1 pump No. 19, KA 1-3920 switching signal relay No. 3920, KA3-1 runs an intermediate relay normally open contact No. 1 pump, 21, KA2-1 starts a pump signal intermediate relay normally open contact, 22, FR1-2 heat relay normally open contact No. 1 pump, 23, FR2-2 heat relay normally open contact No. 2 pump, 24, KA4-4 runs an intermediate relay No. 2 pump, 25, KM2-2 contactor coil No. 2 pump, 26, HG3 running indicator lamp No. 2 pump, 27, KA3-2 runs an intermediate relay normally closed contact No. 1 pump, 28, FR2-1 heat relay normally closed contact No. 2 pump, 29, KM1-1 contactor auxiliary contact No. 1 pump, 30, HG4 overload indicator lamp No. 2 pump, 31, KA1-2 automatically switches a signal intermediate relay normally open contact, 32, KA4-2 runs an intermediate relay normally open contact No. 2 pump, 33, KA2-2 pump signal intermediate relay normally open contact, 34, KA3-3 runs intermediate relay normally open contact No. 1 pump 35, KA1-3 automatically switches signal intermediate relay normally open contact No. 36, KA4-3 runs intermediate relay normally closed contact No. 2 pump No. 37, KA1-4 automatically switches signal intermediate relay No. 38, KA2-3 starts pump signal intermediate relay normally open contact No. 39, K1 starts pump water level switch signal No. 40, KA5-1 stops pump signal intermediate relay normally closed contact No. 41, KA2-4 starts pump signal intermediate relay No. 42, K2 stops pump water level switch signal No. 43, KA5-2 stops pump signal intermediate relay No. 44, HG5 power indicator lamp No. 45, FU2 controls power fuse No. 46.

Detailed Description

The following detailed description of the embodiments of the present invention will be made with reference to the accompanying drawings

The dual-water-pump alternate start-stop control circuit comprises a main loop and a load control loop, wherein the load control loop comprises a manual start-stop loop, an automatic start-stop loop, a fault switching loop, an automatic switching signal loop and a start-stop signal loop.

As shown in fig. 1, the main loop comprises a 380V ac.1 power supply, a No. 1 pump, a No. 2 pump, a No. 1 pump of a contactor of QF1, a KM1, a No. 1 pump of a contactor of 4 and an FR1 thermal relay, a No. 1 pump, a No. 6 pump, a No. 1 motor, an 8V ac power supply, a 380V ac power supply, a No. 1 pump, a No. 2 pump, a No. 3 pump of a power air switch of QF2, a No. 2 pump of a contactor of KM2, a No. 5 pump of a contactor of FR2, a No. 2 pump of; when a QF1 power supply switch No. 1 pump and No. 2 is switched on, a KM1 contactor No. 1 pump and No. 4 is switched on, a No. 1 pump motor and No. 8 run, if a motor fault occurs, an FR1 thermal relay No. 1 pump and No. 6 act and are switched off, and the No. 1 pump motor and No. 8 stop running; similarly, when the QF2 power supply switch No. 2 pump and No. 3 pump is switched on, the KM2 contactor No. 2 pump and No. 5 pump is switched on, and the No. 2 pump motor and No. 9 pump run, if the motor fails, the FR2 thermal relay No. 2 pump and No. 7 pump acts off, and the No. 2 pump motor and No. 9 pump stop running.

As shown in fig. 2, the load control loop at least includes an operation branch, an automatic branch and an overload branch; the operation branch is provided with two groups, namely a pump operation branch 1 and a pump operation branch 2, a KM1-2 contactor coil No. 1 pump No. 17 and a KA3-4 operation intermediate relay No. 1 pump No. 16 in the pump operation branch 1 are connected in parallel and then connected with a KA4-1 operation intermediate relay normally-closed contact No. 2 pump No. 18 and an FR1-1 heat relay normally-closed contact No. 1 pump No. 19 in series, and a KM2-2 contactor coil No. 2 pump No. 26 and a KA4-4 operation intermediate relay No. 2 pump No. 25 in the pump operation branch 2 are connected in parallel and then connected with a KA3-2 operation intermediate relay normally-closed contact No. 1 pump No. 28 and an FR2 motor heat relay normally-closed contact No. 2 pump No. 29 in series; the automatic branch is provided with two groups, namely a No. 1 pump automatic branch and a No. 2 pump automatic branch, wherein in the No. 1 pump automatic branch, KA3-1 operation intermediate relay normally-open contact No. 1 pump.21 and KA1-1 automatic switching signal intermediate relay normally-closed contact.20 are connected in parallel and then are connected in series with KA2-1 start pump signal intermediate relay normally-open contact.22, in the No. 2 pump automatic branch, KA4-2 operation intermediate relay normally-open contact No. 2 pump.33 and KA1-2 automatic switching signal intermediate relay normally-open contact.32 are connected in parallel and then are connected in series with KA2-2 start pump signal intermediate relay normally-open contact.34; the overload branch circuits are provided with two groups, namely a No. 1 pump overload branch circuit and a No. 2 pump overload branch circuit, the No. 1 pump overload branch circuit at least comprises a KM2-1 contactor auxiliary contact No. 2 pump 13, and the No. 2 pump overload branch circuit at least comprises a KM1-1 contactor auxiliary contact No. 1 pump 30; one end of the FU1 control power supply fuse, 10 is connected with a live wire L1, the other end of the FU1 control power supply fuse is connected with a first pin of an SA1 manual automatic mode knob, 11, a second pin of the SA1 manual automatic mode knob, 11 is connected with a first pin of an SA2 manual pump starting knob, 12, a third pin of the SA1 manual automatic mode knob, 11 is connected with one end of a No. 1 pump automatic branch, one end of a No. 2 pump automatic branch, a KA3-3 operation intermediate relay normally-open contact, No. 1 pump, 35 and a KA1-3 automatic switching signal intermediate relay normally-open contact, 36 is connected in parallel, one end of a KA2-3 pump starting signal intermediate relay normally-open contact, 39 and K1 pump starting water level switch signal, 40 is connected in parallel and one end of a K2 pump stopping water level switch signal, 43 is connected, a second pin of the SA2 manual pump starting knob, 12 is connected with one end of a No. 1 pump overload branch, one end, The other end of the No. 1 pump automatic branch, one end of the FR1-2 thermal relay normally-open contact No. 1 pump, one end of the FR2-2 thermal relay normally-open contact No. 2 pump, one end of the 24, the third pin of the SA2 manual start pump knob, 12, one end of the No. 2 pump operation branch, one end of the No. 2 pump overload branch, the other end of the No. 2 pump automatic branch, the other end of the FR1-2 thermal relay normally-open contact No. 1 pump, 23, the other end of the FR2-2 thermal relay normally-open contact No. 2 pump, 24, the KA3-3 operation intermediate relay normally-open contact No. 1 pump, 35, the KA1-3 automatic switching signal intermediate normally-open relay contact, the other end connected in parallel with the KA4-3 operation intermediate relay normally-open contact No. 2 pump, 37 is connected with one end of the KA1-4 automatic switching signal intermediate relay 38 after being connected, the other end of the KA2-3 pump starting signal intermediate relay is normally open, 39 and K1 pump starting water level switch signals, 40 are connected in parallel with the KA5-1 pump stopping signal intermediate relay normally closed, 41 are connected in series and then are connected with one end of a KA2-4 pump starting signal intermediate relay 42, and the other end of a K2 pump stopping water level switch signal, 43 is connected with one end of a KA5-2 pump stopping signal intermediate relay 44; the other end of the No. 1 pump overload branch circuit, the other end of the No. 1 pump running branch circuit, the other end of the No. 2 pump overload branch circuit, the other end of the KA1-4 automatic switching signal intermediate relay, the other end of the KA2-4 pump starting signal intermediate relay, the other end of the KA5-2 pump stopping signal intermediate relay, the other end of the KA 44 is connected with one end of the FU2 control power supply fuse 46, and the other end of the FU2 control power supply fuse 46 is connected to the zero line N; the KM1-2 contactor coil No. 1 pump, the KM2-2 contactor coil No. 2 pump, the KA3-4 operation intermediate relay No. 1 pump, the 16 and the HG2 operation indicator lamp No. 1 pump, the 15 are connected in parallel, the KM2-2 contactor coil No. 2 pump, the 26 and the KA4-4 operation intermediate relay No. 2 pump, the 25 and the HG3 operation indicator lamp No. 2 pump, the 27 are connected in parallel, the KM2-1 contactor auxiliary contact No. 2 pump, the 13 and the HG1 overload indicator lamp No. 1 pump, the 14 are connected in series in the No. 1 pump overload branch, and the KM1-1 contactor auxiliary contact No. 1 pump, the 30 and the HG4 overload indicator lamp No. 2 pump, the 31 are. The FU1 controls a power fuse.10, an HG5 power indicator lamp.45 and an FU2 control the power fuse.46 which are connected in series in sequence, and then two ends of the power fuse are connected with a live wire L1 and a neutral wire N.

As shown in fig. 2, the manual start-stop loop and the fault switching are mainly used for respectively starting and stopping two pumps in a manual mode, only one pump can be started to operate at the same time, if the main pump runs in an overload state, the main pump can be automatically switched to another pump to operate, and meanwhile, the pump overload indicator lamp is turned on. When the No. 1 pump is started and stopped manually, an SA1 manual automatic mode knob is switched to a manual mode, an SA2 manual pump starting knob is switched to a No. 1 pump, a control power supply controls a power fuse through an FU1, the SA1 manual automatic mode knob is switched to an 11, an SA2 manual pump starting knob is switched to a 12, a KM1-2 contactor coil No. 1 pump is operated, a No. 17 and a KA4-1 normally closed contact No. 2 pump are operated, an intermediate relay normally closed contact No. 2 pump is operated, an FR1-1 normally closed contact No. 1 pump is operated, a No. 19 and an FU2 control power fuse 46 form a loop, and at the moment, the KM1-2 contactor coil No. 1 pump is excited, the KM1 contactor No. 1 pump is closed, the No. 1 pump motor is started to operate, the HG2 operation indicator lamp No. 1 pump is turned on; if the No. 1 pump runs normally, the SA2 manual starting pump knob 12 is switched to the No. 2 pump or the cutting position, the No. 1 pump of the KM1-2 contactor coil 17 is demagnetized, the No. 1 pump of the KM1 contactor is switched off, and the No. 1 pump motor 8 stops running. If the No. 1 pump runs normally, FR1 thermal relay No. 1 pump No. 6 overload action is carried out, the No. 1 pump motor No. 8 stops running, the FR1-1 thermal relay normally-closed contact No. 1 pump No. 19 is disconnected, the KM1-2 contactor coil No. 1 pump No. 17 is demagnetized, the KM1 contactor No. 1 pump No. 4 is disconnected, and the HG2 running indicator lamp No. 1 pump No. 15 is turned off; meanwhile, an FR1-2 thermal relay normally-open contact No. 1 pump 23 is closed, a control power supply controls a power supply fuse through an FU1, a 10, SA1 manual automatic mode knob 11, an SA2 manual starting pump knob 12, an FR1-2 thermal relay normally-open contact No. 1 pump 23, a KM2-2 contactor coil No. 2 pump 26, a KA3-2 operation intermediate relay normally-closed contact No. 1 pump 28, an FR2-1 thermal relay normally-closed contact No. 2 pump 29, an FU2 control power supply fuse 46 to form a loop, a KM2-2 contactor coil No. 2 pump 26 is excited, a KM2 contactor No. 2 pump 5 is closed, a No. 2 pump motor 9 is started to operate, an HG3 operation indicator lamp No. 2 pump 27 is bright, the No. 2 pump is displayed to operate normally, and an auxiliary contact No. 2 pump 13 of the KM2-1 contactor is closed, the control power supply fuse is controlled through the FU1, the pump 10, SA1 manual and automatic mode knob.11, SA2 manual pump starting knob.12, KM2-1 contactor auxiliary contact No. 2 pump.13, HG1 overload indicator lamp No. 1 pump.14 and FU2 control power fuse.46 to form a loop, HG1 overload indicator lamp No. 1 pump.14 is lightened to indicate that No. 1 pump is overloaded. When the No. 2 pump is started and stopped manually, an SA1 manual automatic mode knob is switched to a manual mode, an SA2 manual pump starting knob is switched to the No. 2 pump, a control power supply controls a power fuse through an FU1, the SA1 manual automatic mode knob is switched to an 11 SA2 manual pump starting knob, the KM2-2 contactor coil No. 2 pump is switched to 26, the KA3-2 operates an intermediate relay normally closed contact No. 1 pump, the 28, the FR2-1 thermal relay normally closed contact No. 2 pump, the 29 and the FU2 control power fuse 46 to form a loop, and at the moment, the KM2-2 contactor coil No. 2 pump, the KM2 contactor No. 2 pump, the 5 is closed, the No. 2 pump motor, the 9 starts to operate, the HG3 operates an indicator lamp No. 2 pump, the 27 is bright, and the No. 2 pump is displayed to operate normally. If the No. 2 pump runs normally, the SA2 manual starting pump knob 12 is switched to the No. 1 pump or the cutting position, the No. 2 pump of the KM2-2 contactor coil 26 is demagnetized, the No. 2 pump of the KM2 contactor is switched off, and the No. 2 pump motor 9 stops running. If the No. 2 pump runs normally, FR2 thermal relay No. 2 pump.7 overload action is disconnected, the No. 2 pump motor.9 stops running, FR2-1 thermal relay normally-closed contact No. 2 pump.29 is disconnected, KM2-2 contactor coil No. 2 pump.26 is demagnetized, KM2 contactor No. 2 pump.5 is disconnected, and HG3 running indicator lamp No. 2 pump.27 is turned off; meanwhile, an FR2-2 thermal relay normally-open contact No. 2 pump and 24 are closed, a control power supply controls a power supply fuse through an FU1, a 10, SA1 manual automatic mode knob, 11, an SA2 manual starting pump knob, 12, an FR2-2 thermal relay normally-open contact No. 2 pump, a 24, a KM1-2 contactor coil No. 1 pump, 17 and KA4-1 operate an intermediate relay normally-closed contact No. 2 pump, 18, an FR1-1 thermal relay normally-closed contact No. 1 pump, 19 and an FU2 control power supply fuse, 46 forms a loop, a KM1-2 contactor coil No. 1 pump, 17 excitation, a KM1 contactor No. 1 pump and 4 are closed, a No. 1 pump motor is started to operate, an HG2 operation indicator lamp No. 1 pump and 15 is bright, the No. 1 pump is displayed to operate normally, and an auxiliary contact No. 1 pump of the KM1-1 contactor is closed, the control power supply fuse, 10, 685, SA1 manual and automatic mode knob.11, SA2 manual pump starting knob.12, KM1-1 contactor auxiliary contact pump No. 1.30, HG4 overload indicator lamp pump No. 2.31 and FU2 control power fuse.46 to form a loop, HG4 overload indicator lamp pump No. 2.31 is lightened to indicate that pump No. 2 is overloaded.

As shown in fig. 2, the automatic start-stop loop and the fault switching part: the automatic start-stop loop mainly automatically starts two pumps by turns according to the water level condition. If the water level signal of starting the pump arrives, start corresponding pump operation, if the water level signal of stopping the pump arrives, corresponding pump stop operation to if certain pump overload operation appears, can automatic switch to another pump operation, pump overload pilot lamp is bright simultaneously. When the automatic mode is started and stopped, the SA1 manual automatic mode knob.11 is switched to an automatic mode, if a pump starting water level signal arrives, the KA2-1 pump starting signal intermediate relay normally-open contact.22 is closed, the KA2-2 pump starting signal intermediate relay normally-open contact.34 is closed, at the moment, the KA1-1 automatic switching signal intermediate relay normally-closed contact.20 is closed, the KA3-1 operates the intermediate relay normally-open contact No. 1 pump No. 21 is opened, the KA1-2 automatic switching signal intermediate relay normally-open contact.32 is opened, the KA4-2 operates the intermediate relay normally-open contact No. 2 pump No. 33 is opened, a control power supply controls a power supply fuse.10, an SA1 manual automatic mode knob.11, the KA1-1 automatic switching signal intermediate relay normally-closed contact.20, the KA 6-1 pump starting signal intermediate relay normally-open contact.22, the KM1-2 contactor coil No. 1 pump No. 17, KA4-1 operates an intermediate relay normally closed contact pump No. 2, 18, FR1-1 thermal relay normally closed contact pump No. 1, 19 and FU2 control power fuses.46 to form a loop, KM1-2 contactor coil pump No. 1, 17 excitation, KM1 contactor pump No. 1, 4 is closed, a pump No. 1 motor is started to operate, HG2 operation indicator lamp pump No. 1 is lighted, and the pump No. 1 is displayed to operate normally; meanwhile, KA3-4 operates an intermediate relay NO. 1 pump and 16 to excite, KA3-1 operates an intermediate relay normally open contact NO. 1 pump and 21 to be closed, KA1-1 automatically switches signals to automatically switch an intermediate relay normally closed contact NO. 20 to be opened under the action of an automatic switching signal loop, a control power supply controls a power supply fuse through FU1, 10 and SA1 manual automatic mode knobs 11 and KA3-1 operate intermediate relay normally open contact NO. 1 pumps 21 and KA2-1 to start pump signals to normally open contacts NO. 22 of the intermediate relay, KM1-2 contactor coil NO. 1 pumps 17 and KA4-1 operates intermediate relay normally closed contact NO. 2 pumps 18, FR1-1 thermal relay normally closed contact NO. 1 pumps 19 and FU2 to control the power supply fuse 46 to form a loop, and the KM1-2 contactor coil NO. 1 pumps 17 keep exciting. If the overload condition occurs when the No. 1 pump runs, the FR1 thermal relay No. 1 pump 6 overload action, the No. 1 pump motor, 8 stop running, the FR1-1 thermal relay normally-closed contact No. 1 pump, 19 is disconnected, the KM1-2 contactor coil No. 1 pump, 17 is demagnetized, the KM1 contactor No. 1 pump, 4 is disconnected, the HG2 running indicator lamp No. 1 pump, 15 is extinguished, the FR1-2 thermal relay normally-open contact No. 1 pump, 23 is closed, the control power supply controls the power fuse, 10, the SA1 manual automatic mode knob, 11, the KA3-1 running intermediate relay No. 1 pump, 21, KA2-1 starting pump signal intermediate relay contact, 22, the FR1-2 thermal relay normally-open contact No. 1 pump, 23, the KM2-2 contactor coil No. 2 pump, 26, 3-2 running intermediate relay normally-closed contact No. 1 pump, 28, the No. 1 pump, FR2-1 thermal relay normally closed contact No. 2 pump 29, FU2 control power fuse 46 forms a loop, KM2-2 contactor coil No. 2 pump 26 is excited, KM2 contactor No. 2 pump No. 5, No. 2 pump motor.9 starts to operate, HG3 operation indicator lamp No. 2 pump 27 is lighted, it is shown that No. 2 pump operates normally, and the auxiliary contact No. 2 pump of the KM2-1 contactor is closed, the power supply is controlled by a control power supply through FU1, a power supply fuse is 10, an SA1 manual automatic mode knob is 11, KA3-1 runs an intermediate relay normally open contact No. 1 pump, 21, KA2-1 starts a pump signal intermediate relay normally open contact, 22, a KM2-1 contactor auxiliary contact No. 2 pump, 13, an HG1 overload indicator lamp No. 1 pump, 14 and an FU2 control power supply fuse, 46 form a loop, and the HG1 overload indicator lamp No. 1 pump, 14 is bright to indicate that the No. 1 pump is overloaded. If the pump stopping water level signal is reached when the No. 1 pump operates, the KA2-1 pump starting signal intermediate relay normally-open contact is in the 22-off state, the KM1-2 contactor coil No. 1 pump No. 17 is demagnetized, the KM1 contactor No. 1 pump No. 4 is in the off state, the No. 1 pump motor No. 8 stops operating, the HG2 operation indicator lamp No. 1 pump No. 15 is extinguished, the KA3-4 operation intermediate relay No. 1 pump No. 16 is demagnetized, and the KA3-1 operation intermediate relay normally-open contact is in the 1-off state, and the pump No. 21 is in the. If the water level signal of the starting pump arrives again, KA2-1 pump starting signal intermediate relay normally open contact.22 is closed, KA2-2 pump starting signal intermediate relay normally open contact.34 is closed, at the moment, KA1-1 automatic switching signal intermediate relay normally closed contact.20 is opened, KA3-1 operation intermediate relay normally open contact No. 1 pump.21 is opened, KA1-2 automatic switching signal intermediate relay normally open contact.32 is closed, KA4-2 operation intermediate relay normally open contact No. 2 pump.33 is opened, a control power supply controls a power supply fuse through FU1, SA1 manual automatic mode knob.11, KA1-2 automatic switching signal intermediate relay normally open contact.32, KA2-2 pump starting signal intermediate relay normally open contact.34, KM2-2 contactor coil No. 2 pump.26, KA3-2 operation intermediate relay contact No. 1 pump 28, KA3-2 operation intermediate relay contact No. 1 pump, FR2-1 thermal relay normally closed contact No. 2 pump.29, FU2 control power fuse.46 form the return circuit, KM2-2 contactor coil No. 2 pump.26 is excited, KM2 contactor No. 2 pump.5 is closed, No. 2 pump motor.9 starts to operate, HG3 operation indicator lamp No. 2 pump.27 lights, show that No. 2 pump operates normally; meanwhile, KA4-4 operates an intermediate relay No. 2 pump, 25 is excited to act, KA4-2 operates an intermediate relay normally-open contact No. 2 pump, 33 is closed, KA1-2 automatically switches signals to enable an intermediate relay normally-open contact, 32 is opened, a control power supply controls a power supply fuse through FU1, 10 and SA1 manual automatic mode knobs are used for 11 and KA4-2 operate an intermediate relay normally-open contact No. 2 pump, 33 and KA2-2 start pump signals to enable the intermediate relay normally-open contact No. 34, a KM2-2 contactor coil No. 2 pump, 26 and KA3-2 operate an intermediate relay normally-closed contact No. 1 pump, 28, an FR2-1 thermal relay normally-closed contact No. 2 pump, 29 and FU2 control a power supply fuse 46 to form a loop, and the KM2-2 contactor coil No. 2 pump, 26 keeps excited. If the pump No. 2 automatically runs, an overload situation occurs, FR2 thermal relay No. 2 pump.7 overload action, the No. 2 pump motor.9 stops running, FR2-1 thermal relay normally closed contact No. 2 pump.29 is disconnected, KM2-2 contactor coil No. 2 pump.26 is demagnetized, KM2 contactor No. 2 pump.5 is disconnected, HG4 running indicator lamp No. 2 pump.27 is extinguished, FR2-2 thermal relay normally open contact No. 2 pump.24 is closed, a control power supply controls a power supply fuse, SA1 manual automatic mode knob, 11 and KA4-2 running intermediate relay No. 2 pump, 33 and KA2-2 starting pump signals intermediate relay normally open contact No. 2 pump.24, FR2-2 thermal relay normally open contact No. 2 pump, 24, KM1-2 contactor coil No. 1 pump, 17 and 4-1 running intermediate relay No. 2

pump

18, 18, FR1-1 thermal relay normally closed contact pump No. 1, 19 and FU2 control power supply fuses.46 to form a loop, KM1-2 contactor coil pump No. 1, 17 excitation, KM1 contactor pump No. 1, 4 and pump No. 1, 8 start operation, HG2 operation indicator lamp pump No. 1, 15 is on, and the pump No. 1 is displayed to normally operate, and the auxiliary contact No. 1 pump and No. 30 of the KM1-1 contactor are closed, the power supply is controlled by a control power supply through FU1, a power supply fuse is 10, an SA1 manual automatic mode knob is 11, KA4-2 runs an intermediate relay normally open contact No. 2 pump and No. 33, KA2-2 starts a pump signal intermediate relay normally open contact No. 34, a KM1-1 contactor auxiliary contact No. 1 pump and No. 30, an HG4 overload indicator lamp No. 2 pump and No. 31 and an FU2 control power supply fuse and No. 46 form a loop, and an HG4 overload indicator lamp No. 2 pump and No. 31 is bright to indicate that the No. 2 pump. If the pump stopping water level signal is reached when the No. 2 pump automatically operates, the KA2-2 pump starting signal intermediate relay normally-open contact is disconnected at 34, the KM2-2 contactor coil No. 2 pump is demagnetized at 26, the KM2 contactor No. 2 pump is disconnected at 5, the No. 2 pump motor is stopped at 9, the HG3 operation indicator lamp No. 2 pump is extinguished at 27, the KA4-4 operation intermediate relay No. 2 pump is demagnetized at 25, and the KA4-2 operation intermediate relay normally-open contact is disconnected at No. 2 pump at 33. If the water level signal of the starting pump arrives again, the pump No. 1 is started to operate according to the logic, and the like, so that the two pumps can be alternately started to operate.

As shown in fig. 2, the signal loop part is automatically switched: if the No. 1 pump is started, the KA3-3 runs the No. 1 pump of the normally open contact of the intermediate relay, the No. 35 pump is closed, the control power supply controls the power fuse through the FU1, the SA1 manual automatic mode knob, the KA3-3 runs the No. 1 pump of the normally open contact of the intermediate relay, the No. 35 pump, KA4-3 operates an intermediate relay normally closed contact No. 2 pump, No. 37 KA1-4 automatic switching signal intermediate relay, 38 and FU2 control a power supply fuse, 46 forms a loop, KA1-4 automatic switching signal intermediate relay, 38 excitation, KA1-3 automatic switching signal intermediate relay normally open contact, 36 is closed, KA1-1 automatic switching signal intermediate relay normally closed contact, 20 is opened, KA1-1 automatic switching signal intermediate relay normally closed contact, 20 cuts off the No. 1 pump starting loop, and the No. 1 pump is not started when the pump is started next time; meanwhile, the KA1-2 automatic switching signal intermediate relay normally-open contact 32 is closed, and a No. 2 pump starting loop is switched on, so that the No. 2 pump is started when the pump is started next time; when the pump No. 1 stops, the control power supply controls a power supply fuse through FU1, a manual automatic mode knob of 10, SA1, a manual automatic mode knob of 11, KA1-3 automatically switch signals, a normally open contact of an intermediate relay, 36, KA4-3 operate the normally closed contact of the intermediate relay, a pump No. 2, a KA1-4 automatically switch signals, the intermediate relay 38 and FU2 control the power supply fuse 46 to form a loop, and the KA1-4 automatically switch signals, the intermediate relay 38 keeps an excitation state. When the No. 2 pump is started next time, the KA4-3 runs the normally closed contact of the intermediate relay, the No. 2 pump is disconnected, the KA1-4 automatically switches the signal intermediate relay, 38 is demagnetized, the KA1-1 automatically switches the normally closed contact of the signal intermediate relay, 20 is closed, the KA1-1 automatically switches the normally closed contact of the signal intermediate relay, 20 is connected with the No. 1 pump starting loop, so that the No. 1 pump is started next time; meanwhile, the KA1-2 automatic switching signal intermediate relay normally-open contact 32 is disconnected, and the No. 2 pump starting loop is disconnected, so that the No. 2 pump cannot be started when the pump is started next time. According to the logic, the intermediate relay 38 is automatically switched by KA1-4 to control the two pumps to start and stop alternately by field loss and excitation.

As shown in fig. 2, the start stop signal loop section: the starting and stopping signal loop is controlled by two water level switches K1 to start a pump water level switch signal, 40 and K2 to stop the pump water level switch signal, 43, when the water level reaches the starting pump water level, K1 starts the pump water level switch signal, 40 is closed, the control power supply controls a power supply fuse through FU1, 10 and SA1 manual automatic mode knobs, 11 and K1 start the pump water level switch signal, 40 and KA5-1 to stop the pump signal intermediate relay normally closed contact, 41 and KA2-4 to start the pump signal intermediate relay, 42 and FU2 to control the power supply fuse, 46 form a loop, KA2-4 starts the pump signal intermediate relay, 42 is excited, KA2-3 starts the pump signal intermediate relay normally open contact, 39 is closed, KA2-1 starts the pump signal intermediate relay normally open contact, 22 is closed, and KA2-2 starts the pump signal intermediate relay normally open contact, 34 is closed; when the water level changes, a K1 pump starting water level switch signal is disconnected 40, a control power supply controls a power supply fuse through FU1, 10 and an SA1 manual automatic mode knob, 11 and KA2-3 pump starting signal intermediate relay normally-open contacts 39 and KA5-1 pump stopping signal intermediate relay normally-closed contacts 41 and KA2-4 pump starting signal intermediate relays 42 and FU2 control a power supply fuse 46 to form a loop, and the KA2-4 pump starting signal intermediate relays 42 are kept in an excitation state; when the water level reaches the pump stopping water level, a K2 pump stopping water level switch signal 43 is closed, a control power supply controls a power supply fuse through FU1, a 10 SA1 manual automatic mode knob 11, a K2 pump stopping water level switch signal 43, a KA5-2 pump stopping signal intermediate relay 44 and a FU2 control the power supply fuse 46 to form a loop, a KA5-2 pump stopping signal intermediate relay 44 is excited, a KA5-1 pump stopping signal intermediate relay normally closed contact 41 is opened, a KA2-4 pump starting signal intermediate relay 42 is demagnetized, a KA2-1 pump starting signal intermediate relay normally open contact 22 and a KA2-2 pump starting signal intermediate relay normally open contact 34 is opened, and two pumps are controlled to stop respectively.

As shown in fig. 2, the power indication loop part: the power supply indicating circuit mainly comprises an HG5 power supply indicator lamp.45 for indicating the power supply running condition of the load control circuit, if the FU1 controls a power supply fuse.10 to be switched on and the power supply of the load control circuit is normal, the HG5 power supply indicator lamp.45 is on; if FU1 controls power fuse 10 is off or the load control loop power supply is abnormal, HG5 power indicator lamp 45 goes off.

Claims

1. A double-water-pump alternate start-stop control circuit at least comprises a main loop and a load control loop, wherein two water pumps in the main loop are respectively connected with a thermal relay, a contactor and an air switch in series and then connected to an alternating current power supply in parallel; the method is characterized in that: the load control loop at least comprises a manual start-stop loop, an automatic start-stop loop, a fault switching loop, an automatic switching signal loop, a start-stop signal loop and a power supply indicating loop; the manual start-stop loop at least comprises an operation branch; the operating branch is provided with two groups, namely a pump operating branch 1 and a pump operating branch 2, a contactor coil KM1 in the pump operating branch 1 is connected with an intermediate relay KA3 in parallel and then connected with a normally closed contact of a first intermediate relay and a normally closed contact of a first thermal relay in series, and a contactor coil KM2 in the pump operating branch 2 is connected with an intermediate relay KA4 in parallel and then connected with a normally closed contact of a second intermediate relay and a normally closed contact of a second thermal relay in series; the device comprises a main circuit, a pump running branch 1, a pump running branch 2, a power fuse FU2, a manual starting knob SA2, a manual automatic mode knob SA1, a power fuse FU1, a normally closed contact of a first intermediate relay, an intermediate relay KA4, an intermediate relay KA3, two groups of thermal relays, a pump thermal relay 1 and a pump thermal relay 2, wherein one end of the pump running branch 1 is connected with the power fuse FU2 in series and then connected to a zero line N, the other end of the pump running branch 1 is connected with a third pin of the manual starting knob SA2, the first pin of the manual starting knob SA2 is connected with the manual automatic mode knob SA1 and the power fuse FU1 in series and then connected to a live line L1, the normally closed contact of the first intermediate relay is controlled by the intermediate relay KA4, the normally closed contact of the second intermediate relay is controlled by the intermediate relay KA3, the thermal relays are arranged into two; the automatic start-stop loop at least comprises an operation branch and an automatic branch, the automatic branch is provided with two groups, namely a pump automatic branch 1 and a pump automatic branch 2, a first intermediate relay normally-open contact and a signal intermediate relay normally-closed contact in the pump automatic branch 1 are connected in parallel and then connected in series with a first signal intermediate relay normally-open contact, and a second intermediate relay normally-open contact and a second signal intermediate relay normally-open contact in the pump automatic branch 2 are connected in parallel and then connected in series with a third signal intermediate relay normally-open contact; one end of the No. 1 pump automatic branch, which is connected with the No. 1 pump running branch in series, is connected with a third pin of a manual automatic mode knob SA1, and the other end of the No. 1 pump automatic branch is connected with a power fuse FU2 in series and then is connected with a zero line N; one end of the No. 2 pump automatic branch, which is connected with the No. 2 pump operation branch in series, is connected with a third pin of a manual automatic mode knob SA1, the other end of the No. 2 pump automatic branch is connected with a zero line N after being connected with a power fuse FU2 in series, a first pin of the manual automatic mode knob SA1 is connected with a power fuse FU1 in series and then is connected with a live wire L1, a normally closed contact of a signal intermediate relay and a normally open contact of a first signal intermediate relay are controlled by the signal intermediate relay KA1, the normally open contact of the first signal intermediate relay and the normally open contact of a third signal intermediate relay are controlled by the signal intermediate relay KA2, the normally open contact of the first intermediate relay is controlled by the intermediate relay KA3, and; the fault switching loop at least comprises an operation branch circuit, an automatic branch circuit and an overload branch circuit, the overload branch circuit is provided with two groups, namely a No. 1 pump overload branch circuit and a No. 2 pump overload branch circuit, an overload indicator lamp HG1 in the No. 1 pump overload branch circuit is connected with an auxiliary contact of a first contactor in series, and an overload indicator lamp HG4 in the No. 2 pump overload branch circuit is connected with an auxiliary contact of a second contactor in series; a first pin of a manual-automatic mode knob SA1 is connected with a power fuse FU1 in series and then connected with a live wire L1, a second pin of the manual-automatic mode knob SA1 is connected with a first pin of a manual pump starting knob SA2, a third pin of the manual-automatic mode knob SA1 is connected with one end of a No. 1 pump automatic branch and one end of a No. 2 pump automatic branch, a second pin of a manual pump starting knob SA2 is connected with one end of a No. 1 pump overload branch, one end of a No. 1 pump running branch, the other end of the No. 1 pump automatic branch, one end of a first thermal relay normally-open contact and one end of a second thermal relay normally-open contact, a third pin of the manual pump starting knob SA2 is connected with one end of a No. 2 pump running branch, one end of a No. 2 pump overload branch, the other end of the No. 2 pump automatic branch, the other end of the first thermal relay normally-open contact and the other end of the second thermal relay normally-open contact, the other end of the No. 1, The other end of the No. 2 pump operation branch and the other end of the No. 2 pump overload branch are connected to one end of a power fuse FU2, the other end of a power fuse FU2 is connected to a zero line N, an auxiliary contact of a first contactor is controlled by a contactor coil KM2, an auxiliary contact of a second contactor is controlled by a contactor coil KM1, a normally open contact of a first thermal relay is controlled by a No. 1 pump thermal relay, and a normally open contact of the second thermal relay is controlled by a No. 2 pump thermal relay; in the automatic switching signal loop, after a fourth signal intermediate relay normally-open contact and a third intermediate relay normally-open contact are connected in parallel, one end of the fourth signal intermediate relay normally-open contact is sequentially connected with a manual automatic mode knob SA1 and a power fuse FU1 in series and then connected to a live wire L1, and the other end of the fourth signal intermediate relay normally-open contact is sequentially connected with a third intermediate relay normally-closed contact, a signal intermediate relay KA1 and a power fuse FU2 in series and then connected to a zero line N, wherein the fourth signal intermediate relay normally-open contact is controlled by a signal intermediate relay KA1, the third intermediate relay normally-open contact is controlled by an intermediate relay KA3, and the third intermediate relay normally; after being connected in parallel with a normally open contact of a fifth signal intermediate relay, a water level switch signal K1 in the start-stop signal loop is connected in series with a normally closed contact of a fourth signal intermediate relay and a signal intermediate relay KA2 in sequence, and one end of the water level switch signal K2 after being connected in series with a signal intermediate relay KA5 is connected to a third pin of a manual-automatic mode knob SA1, a first pin of the manual-automatic mode knob SA1 is connected in series with a power fuse FU 25 and then connected to a live wire L1, after being connected in parallel with a normally open contact of the fifth signal intermediate relay, a water level switch signal K1 is connected in series with a normally closed contact of the fourth signal intermediate relay and a normally open contact of the signal intermediate relay KA2 in sequence, and the other end of the power fuse FU1 are connected in series to a zero line N, and after being connected in series with the signal intermediate relay KA 63; a normally open contact of the fifth signal intermediate relay is controlled by the signal intermediate relay KA2, and a normally closed contact of the fourth signal intermediate relay is controlled by the signal intermediate relay KA 5; the power source indicating circuit at least comprises a power source indicating lamp HG5, one end of the power source indicating lamp HG5 is connected with the power fuse FU1 in series and then is connected onto the live wire L1, and the other end of the power source indicating lamp HG5 is connected with the power fuse FU2 in series and then is connected onto the zero line N.

2. The dual-pump alternate start-stop control circuit of claim 1, characterized in that: including pilot lamp HG2 in the branch circuit is operated to No. 1 pump at least, pilot lamp HG2 is parallelly connected back and is established ties with first intermediate relay normally closed contact and first thermal relay normally closed contact with contactor coil KM1 and intermediate relay KA3, include pilot lamp HG3 in the branch circuit is operated to No. 2 pump at least, pilot lamp HG3 is parallelly connected back and is established ties with second intermediate relay normally closed contact and second thermal relay normally closed contact with contactor coil KM2 and intermediate relay KA 4.