CN204290278U - A kind of direct current machine field loss protection relay - Google Patents
A kind of direct current machine field loss protection relay Download PDFInfo
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- CN204290278U CN204290278U CN201420742853.8U CN201420742853U CN204290278U CN 204290278 U CN204290278 U CN 204290278U CN 201420742853 U CN201420742853 U CN 201420742853U CN 204290278 U CN204290278 U CN 204290278U
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Abstract
A kind of direct current machine field loss protection relay, comprise step-down transformer T1, full-wave rectification bridge, voltage stabilizing didoe D5, electric capacity C1, electric capacity C2, resistance R1, resistance R2, 555 chips and relay, the output of described step-down transformer is connected with described full-wave rectification bridge, full-wave rectification parallel capacitive C1, between the pin 1 and pin 2 of described 555 chips, difference contact resistance R2 and resistance R1 between pin 2 and pin 5, a voltage stabilizing didoe D5 is connected between pin 5 and pin 1, electric capacity C2 is in parallel with voltage stabilizing didoe D5, the pin 6 of 555 chips is the sampling input of exciting current, it is connected with pin 5, the pin 3 of 555 chips is for relay.The utility model uses element few, and cost is low, to element without particular/special requirement, as long as circuit is installed correctly, gets final product work without the need to adjustment, make also simple, and protection voltage is accurate, strong interference immunity, reliability are high.
Description
Technical field
The utility model relates to a kind of direct current machine field loss protection relay.
Background technology
In some machine tool plants, there is the lathe that a class is such, this lathe uses the electric current of compound-wound magnetic winding to carry out speed governing, and electric current is higher, and rotating speed is slower, and electric current is lower, and rotating speed is faster.When the electric current of excitation winding is too low, motor speed can be very high, Here it is so-called driving.Field loss protection, avoids excitation to cross weak and driving, in case meet accident exactly.
Field loss protection relay uses two 3AX31 type germanium tubes, and leakage current is large, work very unreliable, through be everlasting driving time do not protect or misoperation, cause that motor basket is secondary to be burnt out.The operation principle of this field loss protection relay is the voltage detecting excitation winding sample resistance two ends, and when this voltage is lower than about 2.7V, relay disconnects, lathe stoppage protection; When this voltage is higher than 2.7V, relay closes, lathe can run.Because this circuit does not have hesitation, when sampling voltage is in critical condition, relay can dap, very unfavorable to control loop.
Utility model content
In order to overcome existing the problems referred to above, the purpose of this utility model is that providing a kind of protects a kind of direct current machine field loss protection relay that voltage is accurate, strong interference immunity, reliability are high.
In order to solve the problem, the utility model is by the following technical solutions: a kind of direct current machine field loss protection relay, comprise step-down transformer T1, full-wave rectification bridge, voltage stabilizing didoe D5, electric capacity C1, electric capacity C2, resistance R1, resistance R2, 555 chips and relay, the output of described step-down transformer is connected with described full-wave rectification bridge, full-wave rectification parallel capacitive C1, between the pin 1 and pin 2 of described 555 chips, difference contact resistance R2 and resistance R1 between pin 2 and pin 5, a voltage stabilizing didoe D5 is connected between pin 5 and pin 1, electric capacity C2 is in parallel with voltage stabilizing didoe D5, the pin 6 of 555 chips is the sampling input of exciting current, it is connected with pin 5, the pin 3 of 555 chips is for relay.
Preferably, described resistance R1 is 0.84 with the ratio of the resistance of resistance R2.
The beneficial effects of the utility model are:
1, it uses element few, and cost is low, to element without particular/special requirement, as long as circuit is installed correctly, gets final product work without the need to adjustment, make also simple, and protection voltage is accurate, strong interference immunity, reliability are high;
2, when input voltage is more than relay adhesive during 2.7V, just disconnect lower than during 2.5V, efficiently avoid the shake of relay during input voltage critical condition.
Accompanying drawing explanation
Below in conjunction with drawings and Examples, the utility model is described further:
Fig. 1 is circuit theory diagrams of the present utility model.
Embodiment
Below in conjunction with accompanying drawing, specific embodiment of the utility model is elaborated:
As shown in Figure 1, specific embodiment of the utility model comprises step-down transformer T1, full-wave rectification bridge, voltage stabilizing didoe D5, electric capacity C1, electric capacity C2, resistance R1, resistance R2,555 chips and relay K 1.Wherein, step-down transformer T1 is that 220V turns 12V transformer, and full-wave rectification bridge is made up of diode D1, diode D2, diode D3 and diode D4.
The output of described step-down transformer is connected with described full-wave rectification bridge, full-wave rectification parallel capacitive C1, the output of full-wave rectification bridge and the pin 8 of 555 chips and pin 4 are (in the present embodiment, the numbering of 555 chips is 555 chip corresponding function pin numberings, that is: pin 1 ground GND, pin 2 triggers, pin 3 exports, pin 4 resets, pin 5 control voltage, pin 6 thresholding (threshold value), pin 7 discharge, pin 8 power source voltage Vcc) connect.Between the pin 1 and pin 2 of described 555 chips, respectively contact resistance R2 and resistance R1 between pin 2 and pin 5, the resistance of resistance R1 and resistance R2 is respectively 4.7K Ω and 5.6K Ω, and the ratio of resistance R1 and the resistance of resistance R2 is for being about 0.84.Between pin 5 and pin 1, connect a voltage stabilizing didoe D5, electric capacity C2 is in parallel with voltage stabilizing didoe D5, and the pin 6 of 555 chips is the sampling input of exciting current, and it is connected with pin 5, and the pin 3 of 555 chips is for driving relay K 1.
Its operation principle is as follows:
AC220V civil power, through voltage device T1 step-down, full-wave rectification bridge rectification, C1 filtering, generates the direct voltage of about 13V, to whole circuit supply.Power supply VCC is added on the negative pole of voltage stabilizing didoe D5 through 555 inner 5K Ω resistance, because of the clamping action of D5, make B point current potential by clamper in 2.7V, and A point current potential is due to the dividing potential drop of 2 5K Ω resistance, is its half, i.e. 1.35V.Sampling voltage Uin is Uin × R2/ (R1+R2)=0.54 × Uin in the dividing potential drop of C point.For ease of describing, when supposing just to be energized, sampling voltage Uin rises gradually from 0V.
When Uin is 0V, C point current potential exports high level lower than the comparator below A point (1.35V), and S end is 1, and rest-set flip-flop set, pin 3 exports high level, relay not adhesive.
C point potential voltage rises, and when a C current potential is higher than A point (1.35V), comparator overturns, and S holds input zero, but is low level because now R holds, and rest-set flip-flop maintains the original state due to memory effect, and relay is failure to actuate.
The continuation of Uin voltage is risen, and when it is higher than B point current potential (2.7V), the positive terminal voltage of comparator is above higher than negative terminal, and R holds input high level, and rest-set flip-flop resets, and pin 3 output low level, relay K 1 adhesive, now lathe can work.When Uin continues to keep rising, this state can not change.
Suppose that now Uin is in the decline stage, when it is lower than 2.7V, comparator upset above, R holds input low level, and because now S end is zero, rest-set flip-flop memory previous status, relay K 1 continues to keep adhesive.
When Uin drop to lower than near 2.5V time, C point current potential is lower than 0.54 × 2.5=1.35V, and namely lower than A point current potential (1.35V), the positive terminal potential of comparator is higher than negative terminal.Comparator overturns, and S end puts 1, and rest-set flip-flop puts 1, and pin 3 exports high level, and relay K 1 disconnects, lathe stoppage protection.
It can thus be appreciated that, when input voltage is more than relay K during 2.7V 1 adhesive, just disconnect lower than during 2.5V, efficiently avoid the shake of relay K 1 during input voltage critical condition.
If think amendment protection voltage when using actual, directly can change voltage stabilizing didoe, its voltage stabilizing value is exactly protection value.If can not find suitable voltage-stabiliser tube, can replace with the slightly low voltage-stabiliser tube of voltage stabilizing value, and then forward series connection general-purpose diode or light-emitting diode are finely tuned, a silicone tube of connecting can increase about 0.7V voltage.If want the scope changing hysteresis voltage, the ratio of R1, R2 can be revised.
The above is preferred implementation of the present utility model; for those skilled in the art; under the prerequisite not departing from the utility model principle, can also make some improvements and modifications, these improvements and modifications are also regarded as protection range of the present utility model.
Claims (2)
1. a direct current machine field loss protection relay, it is characterized in that: comprise step-down transformer T1, full-wave rectification bridge, voltage stabilizing didoe D5, electric capacity C1, electric capacity C2, resistance R1, resistance R2, 555 chips and relay, the output of described step-down transformer is connected with described full-wave rectification bridge, full-wave rectification parallel capacitive C1, between the pin 1 and pin 2 of described 555 chips, difference contact resistance R2 and resistance R1 between pin 2 and pin 5, a voltage stabilizing didoe D5 is connected between pin 5 and pin 1, electric capacity C2 is in parallel with voltage stabilizing didoe D5, the pin 6 of 555 chips is the sampling input of exciting current, it is connected with pin 5, the pin 3 of 555 chips is for relay.
2. a kind of direct current machine field loss protection relay according to claim 1, is characterized in that: described resistance R1 is 0.84 with the ratio of the resistance of resistance R2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420742853.8U CN204290278U (en) | 2014-11-29 | 2014-11-29 | A kind of direct current machine field loss protection relay |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201420742853.8U CN204290278U (en) | 2014-11-29 | 2014-11-29 | A kind of direct current machine field loss protection relay |
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| Publication Number | Publication Date |
|---|---|
| CN204290278U true CN204290278U (en) | 2015-04-22 |
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| Application Number | Title | Priority Date | Filing Date |
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| CN201420742853.8U Expired - Fee Related CN204290278U (en) | 2014-11-29 | 2014-11-29 | A kind of direct current machine field loss protection relay |
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| CN (1) | CN204290278U (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104377655A (en) * | 2014-11-29 | 2015-02-25 | 济南职业学院 | Field loss protection relay of direct-current motor |
-
2014
- 2014-11-29 CN CN201420742853.8U patent/CN204290278U/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104377655A (en) * | 2014-11-29 | 2015-02-25 | 济南职业学院 | Field loss protection relay of direct-current motor |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20150422 Termination date: 20151129 |