EP0235050A1 - Control device for electrical apparatuses - Google Patents

Abstract

Device for controlling electrical devices supplied with alternating current, in particular single-phase motors with starting capacitor. The invention relates to devices for controlling electrical devices supplied with alternating current allowing constant powering up, powering down, intermittent powering up by action on push buttons. When the electrical appliance is a single-phase motor with starting capacitor, said device also makes it possible to brake when switching off said single-phase motor, the switching of the starting capacitor of said single-phase motor, as well as the indication of an excess. intensity in said single-phase capacitor motor.

Description

The present invention relates to devices for controlling electrical devices supplied with alternating current, in particular single-phase capacitor motors.

Existing devices have the disadvantages of being composed of complex elements, specific to each use as well as a high cost of implementation.

The object of the present invention is to obtain an economic control device composed in large part of standard elements, which makes it possible to obtain several functions by manual action on one or more push button type controls.

Certain functions can be applied to any electrical device supplied with alternating current; constant power on, intermittent power on, power off the device.

Other functions performed with the present invention apply only to the control of single-phase capacitor motors; switching the capacitor during power-up to ensure starting of said motor, electromagnetic braking during power-down of said motor, detection of an excess of current in said motor.

Another object of the present invention is to be able to connect to said control device for any electrical appliance, safety devices of the electrical contact type causing the switching off of said appliance in order to protect said appliance, for example against excessive heating, or to protect the operator when using said device. The status of the safety devices authorizing or prohibiting the operation of said device can be viewed on one or two indicator lights, for example, red light indicating the prohibition of operation, green light authorizing operation.

According to the invention, the control device comprises a main part called a switch, and a part called a current detector which can be added to form a complete control of a single-phase capacitor motor.

The part called switch is made up of a relay provided with a working contact which makes it possible to switch the AC voltage on the device. The coil of the relay is supplied from the same alternating voltage by placing in series with the coil of said relay a resistor, a closing push-button for starting, and a voltage rectifying diode. A capacitor placed in parallel with the coil of said relay stabilizes the rectified current. The self-supply of said relsi.s is carried out by a circuit composed of an opening push button used for switching off and a diode in series, the assembly connected to the common point of the closing push button and of the coil of said relay, and on the switched terminal of the contact of said relay.

According to the action on the two pushbuttons, the constant running function is obtained, the power off and the intermittent running of said device. Intermittent operation is obtained by pressing the closing push button while holding down the opening push button. If the latter function is not desired, it can be deleted by changing the connection of the two pushbuttons.

According to another characteristic of the part called a switch, the three functions mentioned above can be performed by three push buttons, each having a function. To carry out these three distinct functions, it suffices to add a third push button provided with a working contact and a rest contact as well as a diode mounted in reverse of the two preceding diodes. Intermittent operation is done by action on this push button, causing a current flow in the opposite direction in the coil of said relay, which has the advantage of eliminating a hazard that can occur in other devices with two push buttons and concerning the maintenance of the named switch in constant operation after an operation in intermittent operation.

According to another characteristic of the said switch, it is possible to produce all of the push buttons with one or two conductive blades called tongues and three conductive pads, the assembly being soldered on a printed circuit and com mandated by an insulating part called a handle which makes it possible to perform the three functions mentioned.

According to another characteristic of said switch used for the control of single-phase motor, it is possible, by means of an idle contact of said relay used on said switch, to obtain braking of said single-phase motor with capacitor. This braking is obtained, for single-phase motors with start-up capacitor by switching said start-up capacitor across said single-phase motor using the rest contact of said relay.

According to another characteristic of said switch, it is possible to add, with the circuit described above, safety members of the electrical contact type, the opening of which causes the device to be switched off. The status of these safety devices can be viewed by means of one or two indicator lights. When the said safety contacts are closed, they supply the control circuit of said relay as well as an indicator light, when at least one of said safety contacts is open, the control circuit is no longer supplied and the other indicator light is enlightened. The operator is thus informed of the state of said safety devices and, consequently, of the possibility or not possibility of switching on said device.

According to the invention, the part called current detector mainly applies to the control of a single-phase capacitor motor in addition to the part called switch.

These functions are to switch the capacitor of said single-phase motor to capacitor to effect starting, to switch off said capacitor when said single-phase motor is started and, possibly to indicate the excess current in said single-phase motor using '' an indicator light.

The switching of said starting capacitor is done by means of a relay provided with a work contact and a rest contact.

According to a characteristic of said current detector, a resistance of low value placed in series with the main circuit of said single-phase motor, causes a voltage at its terminals which generates the conduction of a transistor from its emitter base junction when said voltage reaches a certain threshold. To limit the current in the emitter base junction of said transistor, a resistance is added in series on the base of said transistor. To compensate for the temperature effect, add a resistor in series on the emitter and possibly a resistor with a negative temperature coefficient in parallel on the emitter base junction and on the resistor placed on the emitter.

The conduction of said transistor produces the passage of a current rectified by a diode in the coil of said relay which causes the closing of the working contact and the switching of the starting capacitor. A resistance network, zener diode, capacitor placed in parallel on the power supply makes it possible to limit the collector-emitter voltage of the transistor. A capacitor placed in parallel on the relay coil stabilizes the rectified current.

The device called current detector therefore makes it possible, when the single-phase capacitor motor is energized, to switch the capacitor in series on the starting winding of said single-phase motor, following a high current flowing in the main winding of said motor. single phase.

When said single-phase motor is started, the current decreases and the starting circuit which is no longer useful is canceled.

During a mechanical overload or a malfunction of said motor, the intensity increases; the current detector relay is then activated in the same way as for start-up but permanently. An indicator light placed in parallel on the coil of said relay allows the operator to signal this excess intensity, which can avoid deteriorating said single-phase motor.

Other characteristics of said switch and of said current detector composing the present invention will appear on reading the description of the invention, with reference to FIGS. 1, 2, 3, 4 and 5 appended.

In the embodiment shown in fig. 1, described below a control device according to the invention, called a switch, is connected to a single-phase motor 1 having a main winding connected between the terminals B3 and B5 and a starting winding connected between the terminals B3 and B4. A starting capacitor 51 is connected between terminals B4 and B7, said capacitor is switched during startup by the current type current intensity relay RI with its coil connected between terminals B6 and B5, and its switching contact of the connected relay between terminals B5 and B7. Said switch with four terminals B1, B2, B6, and B7, connected to the alternating voltage source S by the terminals B1 and B2, connected to the main circuit of the motor by the terminal B6 and by the common terminal B1 with the terminal B3, said switch connected by terminal B7 to capacitor 51 for braking.

The switch in fig. 1 is in the stop position. The safety contact 31 represents the thermal safety of the motor, closed if the motor does not exceed a limit operating temperature, open otherwise. Safety contact 32 represents a limit switch actuated by the protection screen of the machine driven by said single-phase motor 1 for operator safety. If contacts 31 and 32 are closed, terminal 21 and terminal B1 are at the same electrical potential, the green light 34 is then lit by a current passing through the diode 29, the red light 33 is off, said switch has the possibility of operating. If at least one of the two contacts 31, 32 is open following the absence of the protective screen or an excessive temperature of the motor, the electric current coming from the source S passes through the red indicator 33, the resistor 35 and the diode 29. The resistor 35 is chosen so as to have a low voltage at its terminals which causes the green light 34 to go out, the red light 33 to light up, the switch to be prevented from operating.

When said switch is supplied through safety contacts 31 and 32, the operator has the possibility of carry out the commands using the two push buttons Pl and P2. If said operator activates the closing push button P1, the current from the source S passes through the resistor 22, the coil R1 of the relay, the opening push button P2, the terminal 26, the terminal 25, the closing push button Pl and the diode 29. This current rectified by the diode 29 is stabilized by the capacitor 23 placed in parallel on the coil R1 of the relay and it causes the closing of the working contact TR1 of the relay which energizes the motor 1 by the terminal B6 to through the intensity relay RI. When the operator releases the push button Pl, the relay is held by the current from the source S passing through the contacts 31, 32, the resistor 22, the coil R1 of the relay, the button with opening P2, the diode 27 , and the working contact closed TR1 The motor is under constant voltage.

When said operator activates the push button P2, the current in the relay coil is interrupted, the working contact TR1 of the relay opens, the motor is no longer supplied, the idle contact RR1 closes, switching on the capacitor 51 between the terminals B4 and B5 of the motor 1 through the intensity relay RI, which causes the braking of the motor 1. This braking device can be eliminated by removing the idle contact RR1.

Simultaneous action on the two push buttons Pl and P2 does not produce a current flow in the coil R1 of the relay and therefore has no effect. According to a variant of said switch, the action on the two push buttons P1 and P2 makes it possible to obtain an intermittent power-up. To do this, simply remove the connection between terminals 25 and 26 and make the connection between terminals 24 and 25. The operation of constant energization and de-energization is identical to the previous description, but by intermittent action on the push button P1 while keeping the push button P2 pressed, an intermittent current is obtained in the coil R1 of the relay and consequently the intermittent energization of the motor 1.

The switch for any type of electrical appliance supplied with alternating current, allowing constant powering up, switching off of said electrical appliance by action on two push buttons has the two terminals 21, B1 and B2 connected on the terminals of the source of alternating current S, said electrical appliance with a terminal B3 connected to terminal B1 and a terminal B5 connected to the third terminal B6 of said switch. Said switch comprises a resistor 22 connected to terminal 21, B1 and connected in series with the coil R1 of the relay, an opening push button P2, a closing push button P1 and a diode 29 the cathode of which is connected to terminal B2 . Said switch further comprises a capacitor 23 placed in parallel on the coil R1 of the relay, a diode 27 the anode of which is connected to the common point of the push buttons P1 and P2 and the cathode on the terminal B6, said switch finally comprises the work contact TR1 of said relay connected between terminals B6 and B2.

The switch for any type of electrical device supplied with alternating current, allowing constant powering, intermittent powering up, switching off of said electrical device by action on two push buttons, with two terminals 21, B1 and B2 connected on the terminals of the alternating current source S, said electrical appliance with a terminal B3 connected to the terminal B1 and a terminal B5 connected to the third terminal B6 of said switch. Said switch comprises a resistor 22 connected to terminal 21, B1 and placed in series with the coil R1 of the relay, a push button with closing P1, a diode 29 whose cathode is connected to terminal B2. Said switch further comprises a capacitor 23 placed in parallel on the coil R1 of said relay, an opening push button P2 connected to the common point of the push button P1 and of the coil R1 of said relay, which push button P2 is put in series with a diode 27 whose cathode is connected to terminal B6, said switch finally comprises the working contact TR1 of said relay connected between terminals B6 and B2.

An operational hazard can occur in the assembly described above, when the operator releases the push button P2 before or shortly after the push button Pl, the relay remains triggered by the passage of current in the relay coil by the push button P2 and diode 27.

This operating hazard can be overcome by the assembly shown in fig. 2 by adding to the previous assembly a push button P3 provided with a working contact and a rest contact and with a diode 36 rectifying the current in the in direction. - towards diode 29 or diode 27. The operation of constant energization and de-energization is identical to that of FIG. 1, on the other hand intermittent operation is done by a single push button P3, which when it is activated, circulates a current in the coil R1 of the relay in the opposite direction. When the push button P3 is released, the inversion of the current direction by the diode 27 allows the contact TR1 to drop. The switch fig2 retains the same characteristics regarding the addition of safety contacts 31 and 32, indicator lights 33 and 34, the rest contact RR1 allowing the braking of the single-phase motor.

The switch for any type of electrical appliance supplied with alternating current, making it possible to carry out constant power-up, intermittent power-up, power-off of said electrical device, by action on three push-buttons with two terminals 21, B1 and B2 connected to the terminals of the alternating current source S, said electrical appliance with a terminal B3 connected to terminal B1 and a terminal B5 connected to the third terminal B6 of said switch. Said switch comprises a resistor 22 connected to terminal 21, Bl and placed in series with the coil R1 iu relay, the rest contact of the push button P3, a push button with opening P2, a push button with closing Pl, and a diode 29 whose cathode leads to terminal B2. Said switch further comprises a diode 36 with anode connected to the terminal B2 and cathode connected to the working contact of the push button P3. Said switch finally comprises a diode 27 with cathode connected to the terminal B6 and and anode on the common point of the two push buttons Pl and P2, a capacitor 23 is placed in parallel on the coil R1 of the relay, the working contact TR1 of said relay is connected between the terminals B6 and B2.

Another characteristic of said switch is to be able to economically produce the three push buttons Pl, P2, P3 of FIG. 2 by an assembly soldered on a printed circuit shown in fig. 3 and 4, composed of one or two elastic conductive strips L1 and L2, and three pads P1, P2, P3 conductors. An insulating part P called a controller controls the three functions. The connection of these assemblies shown in fig. 3 and 4 is done in place of the three push buttons P1, P2, P3 in fig. 2, by connecting the blade (s) Ll and L2 to terminal 24, the pad P1 on the terminal 26, the pad P2 on the terminal 25, the pad P3 on the terminal 28. The movement of the lever P in the direction Sl produces constant power-up, in direction S2 first power-off, then more intermittently shifted. The elastic blade L1 brings the part P back to the rest position after each operation.

In the switches described above, it is possible to add safety means for switching off the device comprising at least one safety contact S1 and S2 placed in series between terminal B1 and terminal 21. The means for viewing the state of the safety contacts include an indicator light placed between terminal B1 and terminal 21 and, or, another indicator light 34 placed between terminal 21 and the anode of diode 29, with a resistor 35 placed in parallel with the indicator light 34.

The part called current detector, according to the present invention is shown in fig. 5 with the device named switch. Said current detector is used on the one hand to switch the starting capacity 51 of the single-phase motor 1, and on the other hand to signal using the indicator light 5 * 7 an excess of intensity in the single-phase motor 1.

When power is applied by the device called a switch described above, the intensity of the current flowing in the motor 1 between the terminals B3 and B5 is high. This intensity causes an alternating voltage at the terminals B10 and B8 of the resistor RS causing the conduction on an alternation of the transistor 49 following the current coming from the terminal B8, crossing the resistor 46, the emitter base junction of the transistor 49, the resistor 45 and ending at terminal B10. Due to the conduction of the transistor 49, a current is generated, rectified by the diode 41, passing through the resistor 42, in the coil R2 of the relay, in the emitter-collector junction of the transistor 49 and in the resistor 45. To limit the emitter-collector voltage of the transistor, a zener diode is added between the terminal B11 and B10. To limit the phase shift between the voltage of the source S and the intensity in RS, a capacitor 47 is added between the terminal B11 and B10. Said current flowing in the coil R2 of the relay, stabilized by the capacitor 43 in parallel on said coil, causes the closing of the working contact TR2 of the relay switching the starting capacity 51 and the starting coil of the motor 1. This switching causes the starting motor 1.

After starting the single-phase motor 1, and during normal operation of the motor causing no excess current, the voltage across the terminals of the resistor RS is no longer sufficient to cause the conduction of the transistor 49, and thereby makes the working contact TR2 of the relay opens, the starting circuit is then canceled.

During a mechanical overload or a fault in the motor leading to a significant increase in intensity, the transistor 49 becomes conductive and the coil R2 of the relay is energized, the relay contact TR2 closes in the same way as for starting. In order to signal the operator this excess intensity, a warning light 57 is added in parallel with the coil R2 of the relay.

To compensate for the effect of the temperature on the system, a resistance with a negative temperature coefficient 48 is added between the base of the transistor and the terminal B10, B2.

The switch is characterized in that it is associated with the so-called current detector as shown in fig. 5, for switching the starting capacitor 51 of the single-phase motor. Said current detector comprises a diode 41 whose anode is connected to terminal 21 and connected in series with the resistor 42, the coil R2 of the relay of the current detector, the collector-emitter junction of the transistor 49, a resistor 45 terminating at terminal B2. A capacitor 43 is placed in parallel with the coil R2 of the relay, between the common point of the coil R2 of the relay and the resistor 42, and the terminal B2 is placed in parallel a capacitor 47 and a zener diode 44 with anode on B2. Said _' -detector further comprises a series resistor RS placed between the terminal B2 and the working contact TR1 of the switch relay, a resistor 46 is connected between the base of the transistor 49 and the common point of the resistance RS and the working contact TR1 . Said detector finally comprises the working contact TR2 of the relay connected between the terminals B6 and B9, the starting capacitor 51 connected between the terminals B9 and B4, the rest contact RR2 of said relay connected in series with the rest contact RR1 forming the braking circuit and ending at terminal B9.

The low value RS resistance can be achieved by means of a resistant wire or a printed circuit track.

According to a preferred embodiment of the present invention, all the elements of the so-called switch and of the so-called current detector can be soldered on a printed circuit, reducing the wiring to a minimum and thus forming a complete and economical capacitor motor control device. .

Claims (10)

1 - Switch for any type of electrical device supplied with alternating current, enabling constant powering up, switching off of said electrical device by action on two push buttons. Said switch shown in fig. 1, with two terminals (21, Bl) and (B2) connected to the terminals of the alternating current source (S), said electrical appliance with a terminal (B3) connected to the terminal (B1) and a terminal (B5) connected to the third terminal (B6) of said switch. Said switch comprises a resistor (22) connected to the terminal (21, Bl) and placed in series with the coil (Rl) of the relay, an opening push button (P2), a closing push button (Pl) and a diode (29) whose cathode is connected to the terminal (B2). Said switch further comprises a capacitor (23) placed in parallel on the coil (R1) of the relay, a diode (27) whose anode is connected to the common point of the push buttons (Pl) and (P2) and the cathode on terminal (B6), said switch finally comprises the working contact (TR1) of said relay connected between terminals (B6) and (B2). 2 - Switch for any type of electrical device supplied with alternating current, enabling constant powering up, intermittent powering up, switching off of said electrical device by action on two push buttons. Said switch shown in fig. 1, with two terminals (21, B1) and (B2) connected to the terminals of the alternating current source (S), said electrical appliance with a terminal (B3) connected to the terminal (Bl) and a terminal (B5) connected to the third terminal (B6) of said switch. Said switch comprises a resistor (22) connected to the terminal (21, B1) and connected in series with the coil (R1) of the relay, a closing push button (Pl), a diode (29) whose cathode is connected to the terminal (B2). Said switch further comprises a capacitor (23) placed in parallel on the coil (R1) of said relay, an opening push button (P2) connected to the common point of the push button (Pl) and the coil (RI) of said relay, which push button (P2) is put in series with a diode (27) whose cathode is connected to the terminal (B6), said switch finally comprises the working contact (TR1 ) of said relay connected between terminals (B6) and (B2). 3 - Switch for any type of electrical device supplied with alternating current, enabling constant powering up, intermittent powering up, switching off of said electrical device, by pressing three push buttons. Said switch shown in fig. 2, with two terminals (21, B1) and (B2) connected to the terminals of the alternating current source (S), said electrical appliance with a terminal (B3) connected to the terminal (Bl) and a terminal (B5) connected to the third terminal (B6) of said switch. Said switch comprises a resistor (22) connected to the terminal (21, B1) and placed in series with the coil (R1) of the relay, the rest contact of the push button (P3), an opening push button (P2), a closing push button (Pl), and a diode (29), the cathode of which terminates on the terminal (B2). Said switch further comprises a diode (36) with anode connected to the terminal (B2) and cathode connected to the working contact of the push button (P3), which working contact with its second terminal on the coil (R1) of the relay with a common point with the working contact of the push button (P3). Said switch finally comprises a diode (27) with cathode connected on the terminal (B6) and anode on the common point of the two push buttons (P1) and (P2), a capacitor (23) is put in parallel on the coil (R1 ) of said relay, the working contact (TR1) of said relay is connected between the terminals (B6) and (B2). 4 - Switch according to claim 3 characterized in that the three push buttons (Pl), (P2), (P3) are replaced by one of the systems shown in fig. 3 and 4 composed of one or two blades (L1), (L2), three studs (Pl), (P2), (P3) and an insulating control part (P). The blade (s) (L1) and (L2) are connected to the coil (R1) of the relay, the pad (P1) on the diode (27), the pad (P2) on the diode (36), the stud (P3) on the diode (29). 5 - Switch according to any one of claims 1 to 4 characterized in that safety means for switching off the device comprise at least one safety contact (S1, S2) placed in series between the terminal (B1) and the terminal (21). 6 - Switch according to claim 5 characterized in that means for viewing the state of the safety contacts comprise an indicator light (33) placed between the terminal (B1) and the terminal (21) and, or, another indicator luminals (34) placed between the terminal (21) and the anode of the diode (29), with a resistor (35) placed in parallel with the indicator light (34). 7 - Switch according to any one of claims 1 to 6, characterized in that the electrical device is a single-phase capacitor motor, said single-phase motor with a main winding connected between the terminals (B3) and (B5) and a starting winding connected between terminals (B3) and (B4), said single-phase motor provided with a current relay (RI) whose coil is connected between terminals (B5) and (B6), the contact of said relay d current (RI) is connected between terminals (B5) and (B7), the starting capacitor (51) of said single-phase motor is connected between terminals (B4) and (B7), said switch characterized in that said single-phase motor is braked when switching off by adding a rest contact (RR1) connected between terminals (B6) and (B7) and controlled by the coil (R1) of said relay. 8 - Switch according to any one of claims 1 to 7, characterized in that it is associated with the so-called current detector as shown in fig. 5, for switching the starting capacitor (51) of the single-phase motor. Said current detector comprises a diode (41) whose anode is connected to the terminal (21) and connected in series with the resistor (42), the coil (R2) of the current detector relay, the collector-emitter junction of the transistor (49), a resistor (45) terminating at the terminal (B2). A capacitor (43) is placed in parallel with the coil (R2) of the relay, between the common point of the coil (R2) of the relay and the resistor (42), and the terminal (B2), a capacitor (47) is placed in parallel ) and a zener diode (44) with anode on (B2). Said switch further comprises a series resistor (RS) placed between the terminal (B2) and the working contact (TR1) of the switch relay, a resistor (46) is connected between the base of the transistor (49) and the common point of resistance (RS) and working contact (TR1). Said detector finally comprises the working contact (TR2) of the relay connected between the terminals (Bé) and (B9), the starting capacitor (51) connected between the terminals (B9) and (B4), the rest contact (RR2) of said relay connected in series with the rest contact (RR1) forming the braking circuit and terminating at the terminal (69). 9 - Switch according to claim 8 characterized in that the so-called current detector is temperature compensated by a resistance with negative temperature coefficient (48) placed between the base of the transistor and the terminal (B2). 10 - Switch according to claim 8 or 9 characterized in that the excess current in the motor is displayed by an indicator light (, 7) placed in parallel with the coil (R2) of the relay of said current detector.

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