GB2126440A - Electrical energy saving device for motors - Google Patents
Electrical energy saving device for motors Download PDFInfo
- Publication number
- GB2126440A GB2126440A GB08224938A GB8224938A GB2126440A GB 2126440 A GB2126440 A GB 2126440A GB 08224938 A GB08224938 A GB 08224938A GB 8224938 A GB8224938 A GB 8224938A GB 2126440 A GB2126440 A GB 2126440A
- Authority
- GB
- United Kingdom
- Prior art keywords
- unit
- electrical energy
- motors
- energy saving
- load
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
- H02P23/26—Power factor control [PFC]
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Control Of Voltage And Current In General (AREA)
Abstract
A motor control device comprises a principal circuit system, e.g. a triac with a control circuit system. The principal circuit system includes an input power source, a current-monitoring transducer unit, a motor load, and a triggering device while the control circuit system comprises a signal amplifying unit, a feed-back unit, a firing angle adjusting and indicating unit, a rectifying and filtering unit, a photoelectric coupling unit, an overload protecting unit, and a delay protecting unit. The control circuit system can automatically detect the load state thereof and develop a signal through the system to adjust the firing angle so that proper magnitude of the input voltage is fed to the motor in accordance with different load states; thereby, electrical energy is reduced and the power factor improved. A relay may short circuit the triac under low and excess current conditions. <IMAGE>
Description
SPECIFICATION
Electrical energy saving device for motors
This invention relates to an electrical energy saving device for motors with a principal circuit system incorporated with a control circuit system for automatically adjusting the magnitude of the input power of the motor with respect to the different load states thereof.
Conventionally, all motor control systems have not been provided with specially designed triggering device for controlling the conducting condition of the motor. Therefore, when the motor is in idle running or the load thereof is light, the input current drawn by the motor is still kept at 50-70% of the full-load current, not only consuming too much energy and reducing the power factor of the system, but also decreasing the life span of the motor because of the high temperature suffered by the motor through running. Although control elements, such as SCR and TRIAC, are used in the conventional motor control circuit for triggering the running state of the motor, owing to the fact that the magnitude of the starting current is usually 7-8 times of the zero-load current, the using specification of those control elements must be augmented, causing another burden to the manufacturing costs.On the other hand, a timing device is also used in the conventional control circuit as a starting and overload protecting device, but it has to be matched by an electromagnetic switch, which will increase the substantial volume of the control device as well as the manufacturing costs. Besides, the timing device can effect an overload protection only during starting period, and provides no any protection during the running state of the motor. Furthermore, the conventional motor control circuit system cannot be installed at the front end of the power source switch, and is very inconvenient in utilization, replacement and adjusting operations.
the primary object of this invention is to provide an electrical energy saving device for motors with a principal circuit system incorporated with a control circuit system for automatically adjusting the magnitude of the voltage and current of the motor running under different load states thereof so as to achieve the purpose of saving electrical energy and promoting the power factor of the control system.
Another object of this invention is to provide an electrical energy saving device for motors with an overload protecting circuit for ensuring a safety tripping of the staring current and the over current thereof without impairing the control elements thereof so as to decrease the specification of those control elements and reduce the manufacturing costs as well as the substantial volume of the control circuit system.
Still another object of this invention is to
provide an electrical energy saving device for
motors, which device can be installed in front
of the power source switch for facilitating the
operations of replacement and adjustment.
According to this invention, these and other
objects are achieved by providing an electrical
energy saving device for motors, which device
comprises a principal circuit system incorpor
ated with a control circuit system. The princi
pal circuit system includes an input power
source, a transducer unit, a load, and a trig
gering device while the control circuit system
is electrically combined by a signal amplifying
unit, a feedback unit, a working-point adjust
ing and indicating unit, a rectifying and filter
ing unit, a photoelectric coupling unit, an
overload protecting unit, a phase control unit,
and a delay protecting unit.When the princi
pal circuit system is in a running state, the
control circuit system can automatically detect
the load state thereof, and develop a signal
through the system to adjust the working
point voltage of the phase control unit for
enabling the triggering device of the principal
circuit system to automatically adjust the fir
ing angle along with the magnitude of the
load state for economically consuming the
electrical energy and practically promoting the
power factor of the control system. In addi
tion, an overload protecting unit is incopo
rated into the system for preventing the trig
gering device thereof from suffering the shock
of the over-current incurred in the system.
Other objects, advantages and salient fea
tures of this invention will become apparent
from the following detailed description, which
discloses a preferred embodiment of the pre
sent invention with reference to the annexed
drawings, in which:
Figure 1 is a block diagram of an electrical
energy saving device for motors embodying
this invention;
Figure 2 is a circuit diagram of a principal
circuit system according to this invention;
Figure 3 is a circuit diagram of a control
circuit system according to this invention;
Figure 4 is a circuit diagram of a power
supply unit matched between the principal
circuit system of Fig. 2 and the control circuit
system of Fig. 3; and
Figure 5 is an operational illustration of the
preferred embodiment according to this inven tion.
Referring to Fig. 1, a block diagram illus
trates a preferred embodiment of an electrical
energy saving device for motors according to
this invention, and comprises in combination
with two major parts-a principal circuit sys
tem and a control circuit system. The principal
circuit system includes an input power source
(not shown), a transducer unit, a load (motor),
and a triggering device (not shown) while the control circuit system is electrically combined by a signal amplifying unit, a feedback unit, a working-point adjusting and indicating unit, a rectifying and filtering unit, a photoelectric coupling unit, an overload protecting unit, a phase control unit, and a delay protecting unit.When the load of the principal circuit system is in running state, a dynamic signal thereof will be transfered to the control circuit system by the transducer unit and fed to the signal amplifying unit thereof for amplification and being rectified through the rectifying and filtering unit, and then, with the conversion processing by the photoelectric coupling unit, the rectified signal will directly drive the phase control unit, and actuate the triggering device to automatically adjust the magnitude of the firing angle along with the signal of the load state for further adjusting the running power of the motor thereof. Moreover, by means of the working-point adusting and indicating unit, the working-point voltage can be set for establishing the most favorable potential, and, by means of the feedback unit, the adjusted working-point voltage can be maintained at a constant state thereat.In addition, the overload protecting unit incorporated therein is used for preventing the whole system from suffering the shock of the over-load current thereof and also for reducing the using specification and volume of the triggering device.
The circuit diagram of the principal circuit system is shown in Fig. 2, which includes an input power source, a transducer unit, a load
M, and a triggering device. One node U of the transducer unit is connected to a terminal
X of the power source, and the other node V to one end of the load M, of which the other end is coupled with the triggering device through the node m of a photo-sensitive resistor CdS, thereof. The Triggering device further comprises a DIAC, a TRIAC, a pair of demagnetizing points B and C of a relay unit arranged thereto, and some necessary resistors and capacitors electrically coupled therewith.
The node n of the photosensitive resistor CdS1 is connected to one end of the DIAC, of which the other end is coupled with the gate G of the TRIAC, where the anode A and the cathod
C are respectively connected in parallel with the demagnetizing points B and C of the relay unit arranged in the control circuit system.
A detailed circuit diagram of the control circuit system of the preferred embodiment according to this invention is shown in Fig. 3, wherein the main components include a signal amplifying unit, a feedback unit, a recitfying and filtering unit, a photoelectric coupling unit, a working-point adjusting and indicating unit, an overload protecting unit, and a delay protecting unit.The input signal coming from the transducer unit of the principal curcuit system through the nodes U and V is picked up by the control circuit system by means of a transformer Tr2 coupled with the signal am
plifying unit, which is combined by a pair of transistors Q, and Q2 electrically connected therein and a plurality of resistors and capacitors electrically coupled therewith; wherein, the base of the transistor Q, is connected to a
variable resistor VR, of the transformer Tr2, the emitter to the ground through a resistor
R8, and the collector to the base of the transistor Q2 through a capacitor C4 and two
parallel-connected resistors R5 and R7.The
feedback unit, which mainly includes a polar
capacitor C9 and a photosensitive resistor Cods,. is connected to the signal amplifying
unit by connecting one end of the CdS2 to the
collector of the transistor Q2, and the negative
end of the capacitor C9 to the emitter of the
transistor Q,. The rectifying and filtering unit
combined by a diode D1 and two capacitors C5
and C6 is connected to the signal amplifying
unit and the feedback unit through the posi
tive end of the capacitor C5 at one node, and
coupled with the photoelectric coupling unit,
which includes a Darlington amplifier Q3, 4, a lamp LP, and a red indicator LED,, at the
other node P connected to the base of the
transistor Q3.In this connection, the light
source of the lamp LP will be sensed by the
photosensitive resistor CdS, of the principal
circuit system, and the red indicator LED, will
indicate the conducting state of the control
circuit system. The working-point adjusting
and indicating unit combined by a darlington
amplifier Q5, Ofi and a yellow indicator LED2
is disposed therein by connecting the base of
the transistor Q5 to the base of the transistor
Q3 of the photoelectric coupling unit, and the
cathod of the yellow indicator LED2 to the
emitters of the transistors Q5 and Q6 for
indicating the normal state of the working
point voltage thereof.The overload protecting
unit includes a PNP transistor Q7, a Darlington
amplifier 08, Q9, a relay RY having a plurality
of contacting points A, B, C, and a green
indicator LED3, wherein, the base of the tran
sistor Q7 is connected to the base of the
transistor Q3 and Q5 through a variable resis
tor VR2, the emitter to the ground, and the
collector to the base of the Darlington transis
tor Q8 while the cathod of the green indicator
LED3 is connected to collectors of the transis
tors Q8 and Qg thereof. One node of the relay
RY is connected to the cathod of the LED3 and
the other node to the collectors of the transis
tors 0, and Qg. Besides, the contacting points
A, C of the relay RY are the exciting points
and points B, C the demagnetizing points,
which are coupled with the triggering device
of the principal circuit system.
A power supply circuit of the control circuit
system is shown in Fig. 4, wherein, the
secondary winding of the transformer Tr, is
coupled with a bridge-rectifier circuit, of
which the common output node is grounded
and the other common output node connected
to a pair of rectifying capacitors C2, and C22.
I The positive terminal of C22 is connected to the positive terminal of a yellow indicator LED4, of which the negative end is coupled with the photoelectric coupling unit through the collectors of the Darlington transistors Q3, 04 so as to directly respond to the illumination of the lamp LP thereof.
The operational principle of the preferred embodiment according to this invention is as follows:
Referring to Figs.'s 2, 3, and 4, when the load (motor) of the principal circuit system is zero or in idling state, the current drawn by the load is weak so that the signals produced at the nodes U and V of the transducer unit are also weak. After these weak signals are picked up and amplified by the signal amplifying unit and also filtered by the rectifying and filtering unit of the control circuit system, a
DC voltage Vp will appear at the node P.As these amplified signals are still weak due to the zero load or idling state in the system, the
DC voltage value appeared at the node P will be too small to energize the Darlington amplifier Q3, Q4 so that the lamp LP will not illuminate thereat, and the resistance present at the photosensitive resistor CdS, in the principal circuit will be very high. As a result, the firing angle a of the TRIAC in the triggering device is increased while the conduction angle B thereof decreased, and, henceforce, the terminal voltage and current of the load (motor) is reduced; thereby, economical consumption of electrical power is effected therewith.
When the load (motor) of the principal circuit system is full, the signal strength passing through the nodes U and V of the transducer unit will be increased, and, after being amplified and filtered by the control circuit system, a DC voltage Vp appearing at the node P will be high enough to turn on the
Darlington amplifier Q3, Q4 so that the lamp
LP will illuminate, and the resistance of the photosensitive resistor CdSr will suddenly drop; consequently, the firing angle a of the
TRIAC thereof is decreased while the conduction angle 8 increased, and the terminal voltage and current of the load are therefore incremented therein for effecting the normal running thereof.
In case of an over-current appearing in the input of the system, for preventing the TRIAC thereof from being burnt out, the voltage present at the node P can be set at a level that it will not energize the Darlington amplifier Q8, Q9 of the overload protecting unit but just actuate the demagnetizing points B and C of the relay RY thereat. Therefore, the overload current appearing in the principal circuit system will just flow through the loop formed by the points B and C of the relay RY without flowing through and damaging the TRIAC, effecting the production therewith.
Referring to Fig. 5, an operational illustration of the preferred embodiment according to this invention indicates that, if this device is required to operate in accordance with the logic sequence, first, the output voltage V at the node P of the rectifying and filtering unit must be set through adjustment which can be made by adjusting the variable resistor VR1, and the working-point votages obtained therefrom will generally fall into three levels as follows:
The voltage of the first level is Vp < 1 V. At this stage, the TRIAC of the triggering device in the principal circuit system will not operate;
The voltage of the second level is 1Vp < 5V, which is the operational range of the TRIAC thereof; and
The voltage of the third level is Vp > 5V. In this stage, the TRIAC will not operate. Therefore, when the system is not in normal load state that makes the voltage level at the node
P as being Vp < 1 V, the transistor Qao of the delay protecting unit in the control circuit system will be cut off with a high potential appearing at its collector for turning on the transistor Q", of which the low potential appraring at the collector will, in turn, cut off the Darlington transistors 09, Qg of the overload protecting unit.Meanwhile, the high potential at the colletors of Q8 and Qg will make the relay RY restore to the state at demagnetizing points B and C, becoming a by-pass to the triggering device of the principal circuit system. On the other hand, as the lamp LP of the photoelectric coupling unit is not in a illuminating state, the resistance of CdS, is too high to energize the triggering device of the principal circuit system.When the motor is in idling state, the variable resistor VR, will be adjusted beforehand for making the voltage Vp at the node P rising to a level of about 1.6-1.8 VDC, then, the Darlington transistors
Q5, Q6 of the working-point adjusting and indicating unit will be turned on, and the yellow indicator LED2 will be illuminating so as to show that the firing angle a of the triggereing device of the principal circuit system is closing to a state of 90"-100", presenting as favorable working-point voltage thereat.At this stage, the variable resistor VR, can be fixed thereat, and the transistor Qao of the delay protecting unit is turned on, leaving its collector in a state of negative potential capable of cutting off the transistor Q", of which the high potential appearing at the collector will turn on the Darlington transistors Q8, Qg of the overload protecting unit. In the meantime, the low potential state at the collectors of Q8 and Qg will make the relay RY thereof return to the state at exciting points A and C. At the same time, the Darlington transistors Q3, Q4 of the photoelectric coupling unit will also be turned on, and the lamp LP gradually illuminates, causing the resistance of the photosensitive resistor CdS, to reduce by degrees. Consequently, the triggering device of the principal circuit system starts to perform the operations of triggering and conduction.
When the load of the motor is steadily increasing, the signal strength at the output of the transducer unit will also be growing; therefore, the voltage at the node P rises and drives the Darlington ransistors Q3, Q4 to increase the amplified signals therefrom, causing the resistance of the photosensitive resistor CdS, to make a further decrease thereat, and, henceforth, the firing angle a of the
TRIAC is reduced while the conduction angle 8 increased, effeting automatic adjustment thereat following the magnitude of the load state thereof.Moreover, owing to the fact that the adjustment of the variable resistor VR2 is not in excess of 5V, the transistor Q7 of the overload protecting unit remains at cut-off state while the transistors Q8 and Qg are still in a ON state, making the relay RY being kept at the state of exciting points A and C.
When an over-current condition appears in the system and causes a voltage level at node
P to be in a state of Vp > 5V, the transistor Q7 of the overload protecting unit will be turned on, developing a low potential across the collector of the transistor Q7 so that the Darlington amplifier Q8, Qg is cut off, making the relay RY restoring to the state at demagnetizing points B and C; therefore, the over-current thereof is shunted from the triggering device of the principal circuit system through a bypass formed thereat, effecting protection operations therewith.
According to the preferred embodiment of this invention, when the power source switch is turned on, a great volume of current will be instantaneously drawn by the load thereof, making the voltage at the node P as being Vp > 5V. Upon the load becoming stable, the voltage at node P will return to the state between 1V-5V. In order to avoid causing the relay RY to transfer between the points B yA in such a short time duration and affecting the life span of the TRIAC element or producing undesirable impulse in the system, a capcitor C7 and a pair of transistors Q1O and Qtt are disposed in the delay protecting unit so as to eliminate the instantaneous skip transfer operation and maintain the system in normal work.Besides, owing to the matched operations of the transistor Q", which is turned on only when Vp < 1V, and the transistors Og and Q9, which are turned on only when Vp > 5V, 5V, the working voltage is always kept at the state of 1V < Vp < 5V for performing normal operations.
Furthermore, according to the preferred embodiment of this invention, when a load is added to the system, a chained alternation relationship of the system is as follows:
This positive feedback relationship caused by the rising of the line current in following the addition of the load thereof is not adjusted in linear proportion, so that, it will affect more or less the stability of the circuit working-point voltage. However, with the feedback unit provided in the control circuit system, the abovementioned positive current rising problem is solved by the negative feedback signals produced therefrom, and the working-point voltage of this system can always be kept at an adjustable stability in accordance with the load of different types of motor used thereat.
Therefore, when the illumination of the lamp
LP in the control circuit is intensifying along with the increase of the load thereof, the brighness of the indicator LED4 in the feedback unit will also increase, causing the resistance of the photosensitive resistor CdS2 to decrease; therefore, the current rising phenomenon at the node P is offset, and the stability of the working-point voltage always adjustably maintained thereat.
While a preferred embodiment has been chosen and described, it will be apparent that many changes may be made in the general construction and arrangement of this invention without departing from the spirit and scope thereof, and it is therefore desired that this invention be not limited to the exact disciosure, but only to the extent of appended
Claims (11)
1. An electrical energy saving device for motors comprising in combination:
a principal means responsive to different load states for performing signal transducing and power factor adjusting operations; and
a control means electrically incorporated with said principal means for automatically processing the transduced signals from said principal means and providing a most favorable potential for said principal means to effect the adjustment of power factor according to different load states of the motor thereof for economical energy consuming, and to prevent the elements thereof from suffering over-current impulsion for extending the life span of the motor thereof.
2. An electrical energy saving device for motors as claimed in Claim 1 wherein said principal means further comprises a transducer unit connected between the input power source and the load thereof, and a triggering device electrically coupled with said load and said input power source.
3. An electrical energy saving device for motors as claimed in Claim 2 wherein said triggering device further comprises a photosensitive resistor with one end connected to the load, a DIAC with one node connected to the other end of said photosensitive resistor, a
TRIAC with the gate connected to the other terminal of said DIAC, and a plurality of demagnetizing points of a relay unit respectively connected in parallel to the anode and cathod of said TRIAC through a plurality of resistors and capacitors disposed therein with respect to said input power source, whereby, the conduction angle of said TRIAC can be automatically controlled by the resistance magnitude of said photosensitive resistor for adjusting the power factor required for said load.
4. An electrical energy saving device for motors as claimed in Claim 1 wherein said control means further comprises:
a power supply unit;
a signal amplifying unit associated with said transducer unit of said principal means;
a feedback unit electrically connected to said signal amplifying unit and said power supply unit for providing negative feedback signals therefrom;
a rectifying and filtering unit coupled with said signal amplifying unit and said feedback unit;
a photoelectric coupling unit electrically connected to said rectifying and filtering unit with respect to said signal amplifying unit;
a working-point adjusting and indicating unit electrically connected to said photoelectric coupling unit and said rectifying and filtering unit;
an overload protecting unit coupled with said working-point adjusting and indicating unit and said photo-electric coupling unit; and
a delay protecting unit coupled with said overload protecting unit and said photoelectric coupling unit.
5. An electrical energy saving device for
motors as claimed in Claim 4 wherein said feedback unit combined mainly by a polar capacitor and a photosensitive resistor is characterized in that the resistance reducing of said photosensitive resistor with respect to the
current rising state of said power supply unit will provide a negative feedback signal for
maintaining the stability of the working-point voltage thereof.
6. An electrical energy saving device for
motors as claimed in Claim 4 wherein said
rectifying and filtering unit is characterized by
a node, of which the voltage can be adjusted for controlling the logic operations of said
control means.
7. An electrical energy saving device for
motors as claimed in Claim 4 wherein said
phtooelectric coupling unit furthere camprises
a Darlington amplifier matched with a lamp
and an LED indicator for controlling the firing
angle condition of said triggering device in
said principal means and indicating the nor
mal state of the load thereof.
8. An electrical energy saving device for
motors as claimed in Claim 4 wherein said
working-point adjusting and indicating unit
further comprises a Darlington amplifier coup
led with an LED indicator for presenting a favorable working-point voltage when the motor being in idling state and the firing angle of said triggering device in said principal means closing to 90"-100" thereat.
9. an electrical energy saving device for motors as claimed in Claim 4 wherein said overload protecting unit furtter comprises a
Darlington amplifier electrically coupled with a relay unit having exciting and demagnetizing points, an LED indicator, and a PNP transistor, and is characterized in that, when an over-current passing through the load thereof, said Darlington amplifier will be cut off, and said relay unit will restore to the state at demagnetizing points for providing a by-pass to said triggering device of said principal means and achieving overload protecting purpose therewith.
10. An electrical energy saving device for motors as claimed in claim 4 wherein said delay protecting unit is characterized in that it is operable only on low potential level for matching with said overload protecting unit, which is operable only on high potential level, so as to maintain the system always in normal operational condition between low potential level and high potential level, and to effect the protection therewith.
11. An electrical energy saving device for motors constructed and arranged substantially as hereinafter described with reference to and shown in the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08224938A GB2126440A (en) | 1982-09-01 | 1982-09-01 | Electrical energy saving device for motors |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08224938A GB2126440A (en) | 1982-09-01 | 1982-09-01 | Electrical energy saving device for motors |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2126440A true GB2126440A (en) | 1984-03-21 |
Family
ID=10532626
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08224938A Withdrawn GB2126440A (en) | 1982-09-01 | 1982-09-01 | Electrical energy saving device for motors |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2126440A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1294696C (en) * | 2004-07-23 | 2007-01-10 | 南阳孚达光电技术有限公司 | Intelligent three-phase asynchronous motor power-saving protector |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3443188A (en) * | 1967-02-27 | 1969-05-06 | Rca Corp | Switching circuits |
| GB1393076A (en) * | 1972-03-03 | 1975-05-07 | Malte Manson Ab | Series ac commutator motor with regulated speed |
| GB1464792A (en) * | 1973-03-10 | 1977-02-16 | Bosch Gmbh Robert | Electrical speed regulating arrangement for an alternating- current motor |
| US4052648A (en) * | 1976-07-19 | 1977-10-04 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Power factor control system for ac induction motors |
| GB1505734A (en) * | 1974-02-16 | 1978-03-30 | Bosch Gmbh Robert | Regulators for electric motors |
| GB2064240A (en) * | 1979-11-21 | 1981-06-10 | Duepro Ag | Utensil for cleaning floor coverings |
| WO1981002651A1 (en) * | 1980-03-05 | 1981-09-17 | Scott & Fetzer Co | Simplified power factor controller for induction motor |
-
1982
- 1982-09-01 GB GB08224938A patent/GB2126440A/en not_active Withdrawn
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3443188A (en) * | 1967-02-27 | 1969-05-06 | Rca Corp | Switching circuits |
| GB1393076A (en) * | 1972-03-03 | 1975-05-07 | Malte Manson Ab | Series ac commutator motor with regulated speed |
| GB1464792A (en) * | 1973-03-10 | 1977-02-16 | Bosch Gmbh Robert | Electrical speed regulating arrangement for an alternating- current motor |
| GB1505734A (en) * | 1974-02-16 | 1978-03-30 | Bosch Gmbh Robert | Regulators for electric motors |
| US4052648A (en) * | 1976-07-19 | 1977-10-04 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Power factor control system for ac induction motors |
| GB2064240A (en) * | 1979-11-21 | 1981-06-10 | Duepro Ag | Utensil for cleaning floor coverings |
| WO1981002651A1 (en) * | 1980-03-05 | 1981-09-17 | Scott & Fetzer Co | Simplified power factor controller for induction motor |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1294696C (en) * | 2004-07-23 | 2007-01-10 | 南阳孚达光电技术有限公司 | Intelligent three-phase asynchronous motor power-saving protector |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |