CN2187349Y

CN2187349Y - Phase fault contactless protector for electric machines

Info

Publication number: CN2187349Y
Application number: CN 93246592
Authority: CN
Inventors: 王福海
Original assignee: Individual
Current assignee: Individual
Priority date: 1993-12-25
Filing date: 1993-12-25
Publication date: 1995-01-11
Anticipated expiration: 2003-12-25

Abstract

The utility model relates to a phase fault protector for a motor. The phase fault protector for a motor principally aims that connections which are connected in series in a main control loop frequently are out of control because of oxidation, corrosion, and bad contact in the existing phase fault protection measures of the motor, and discloses a phase fault contactless protection circuit for a motor. The phase fault protector for a motor is characterized in that an on-off element is connected in series in the main control circuit; the on-off element takes phase current induced voltage as signals which are output by an and circuit to control the on-off element to switch on or switch off; the phase fault contactless protection circuit for a motor comprises a detection circuit, the and circuit, a direct current power supply, and the on-off element, and is provided with the two grounding methods of a common ground and a division common ground. The trigger voltage of the on-off element is taken out from the division common ground. Thus, when the motor runs, the motor can not be burnt out because of phase fault.

Description

Phase fault contactless protector for electric machines

The present invention relates to threephase asynchronous, prevent the protective device that is burnt because of phase shortage.

During the threephase asynchronous running, often burnt because of phase shortage and cause very large economy loss, people once made multiple open phase protector of motor for addressing this problem, and all played better action.But also have weak point, common way is in the motor main control loop, a kind of voltage-controlled contact of its phase shortage, method of protecting motor not ruined because of phase shortage of being subjected to of connecting.Facts have proved because of the contact area little; limited by action frequency, use after the certain hour, contact oxidation blackout is perishable; especially (printing and dyeing, chemical industry etc.) are used in the etchant gas environment is arranged; this kind phenomenon is even more serious, causes contact loose contact, arcing, is directed at that contact is burnt out or sticking connection; make main control loop lose protective effect; cause machine operation undesired, it is shorter to have the contact protective device life-span thus, undesirable.

The objective of the invention is to overcome above-mentioned shortcoming, and propose the contactless protective device of a kind of motor phase shortage.

For solving above-mentioned task, the present invention proposes following scheme:

Promptly between phase line and zero line, by fuse, A.C. contactor, normally closed button, often drive button, main control loop when being unified into motor rotation successively, a kind of switch element of series connection in this loop, be this element on-off, if a kind of circuit that is subjected to its phase voltage control, said switch element is bidirectional triode thyristor or same function element.

Said control circuit comprises:

Being used to detect phase current provides signal for AND, and by three coils that have magnet ring, motor three-phase power (A, B, C) was therefrom gone here and there, this coil one end ground connection, and the other end is connected on the diode negative terminal respectively, and filter capacitor constitutes signal deteching circuit;

In order to enlarge the scope of application, at the diode anode, respectively add the voltage-stabiliser tube that a power is fit to, when low-power machine was worked, to force down voltage-stabiliser tube inoperative because of induced electricity, when heavy-duty motor is worked, induced voltage is higher on identical coil, and voltage-stabiliser tube just works, and makes triode base stage input voltage still in normal range (NR), guarantee the triode operate as normal, so it is very wide to use the protector range of application of this protective circuit manufacturing; When phase shortage, also there is certain negative pressure because of filter capacitor is instantaneous, for corresponding triode is ended fast, also be provided with the resistance that resistance is appropriate in parallel with filter capacitor, when phase shortage not, do not influence the triode operate as normal again, and during phase shortage, can bleed off the instantaneous negative pressure of depositing of filter capacitor very soon by this resistance again, end fast thereby reach triode.Voltage-stabiliser tube, filter capacitor, discharge resistance parallel connection, an end ground connection, another termination diode cathode and current-limiting resistance one end, and constitute and door three input circuits;

Being used to form AND provides control signal for switch element, by current-limiting resistance (R _4-6), biasing resistor (R _7-9), and resistance (R ₁₀), triode (Q _1-3) AND circuit that constitutes, this circuit current-limiting resistance one end connects with diode cathode, the same triode (Q that is connected to of the other end and biasing resistor one end _1-3) base stage on, biasing resistor other end ground connection, triode (Q _1-3) series connection each other, the triode (Q of position, end ₃) emitter promptly is connected to zero line, passes through resistance (R again ₁₀) ground connection;

Be used to AND circuit that power supply is provided and set up trigger voltage, form DC power supply by transformer, diode, filter capacitor, resistance for switch element.For obtaining positive trigger voltage, this circuit is divided into two kinds of ground connection, i.e. the public ground of transformer secondary coil one termination (G ₁), and the positive pole of filter capacitor meets the public ground of branch (G ₂), the negative terminal of its DC power supply and triode (Q ₁) collector electrode joins, and divides to be connected to the SCR control utmost point publicly, when the AND circuit operate as normal, divide publicly to position, end triode (Q ₃) emitter has trigger voltage output, controllable silicon could conducting, and when phase shortage, trigger voltage is zero, and controllable silicon is closed.

This programme compared to existing technology; has following progress: in main control loop; because of the switch element (bidirectional triode thyristor) of connecting; thereby overcome in the present protective device technology because of being provided with the series connection contact; the above-mentioned weak point that is caused; again because of this protective circuit; pressure limiting and arresting element have been adopted; use this protective circuit; the open phase protector of motor of making; the scope of application is very wide, and quick action has also that volume is little, in light weight, safe and reliable, price is low, noiseless, efficient height, power consumption are low, long service life, advantage such as easy to installation and maintenance.

Below in conjunction with accompanying drawing, the present invention is described further:

Figure is the contactless protective circuit schematic diagram of motor phase shortage of the present invention.

As seen from the figure, by fuse (RD ₄), A.C. contactor (C), normally closed button (TA), often drive button (QA) and form main control loop, insert between phase line and the zero line, and often opening between finger contact, these element through and off of a bidirectional triode thyristor (TLC) in parallel are controlled by following circuit, and the voltage that is used to detect phase current induction output provides signal for AND, three coil (L that have magnet ring _1-3), motor three-phase power (A.B.C) seals in respectively among this coil, this coil one end ground connection, another terminating diode (D _1-3) negative pole, and filter capacitor (C _1-3) testing circuit formed; Be used for pressure limiting and guarantee the triode operate as normal or end fast, by voltage-stabiliser tube (D _5-7), electric capacity (C _1-3), resistance (R _1-3) parallel connection, a terminating diode (D _1-3) anodal and current-limiting resistance (R _4-6) between, other end ground connection; Being used to form AND is that switch element (TLC) provides control signal, by current-limiting resistance (R _4-6), biasing resistor (R _7-9), triode (Q _1-3), resistance (R ₁₀), constitute AND circuit, the triode (Q in this circuit _1-3) series connection each other, triode (Q ₃) emitter promptly wants the connecting to neutral line again through resistance (R ₁₀) ground connection: AND circuit and switch element provide direct current and trigger voltage, by transformer (T), diode (D ₄), filter capacitor (C _4-5), resistance (R ₁₀) DC power supply formed.The transformer secondary coil, the public ground of a termination (G ₁), electric capacity (C _4-5) positive pole meets the public ground of branch (G ₂) and be connected to controllable silicon (TLC) the control utmost point.

According to figure as can be known when pressing start button (QA), A.C. contactor (C) action, this moment motor rotation, three coil (L _1-3) induced voltage is arranged at once, respectively by rectification two utmost points and filter capacitor,, be added on the base stage of triode through current-limiting resistance, make the triode normally, this moment is at triode (Q ₃) emitter, just produce trigger voltage to dividing publicly, supply with the bidirectional triode thyristor trigger electrode, make the controllable silicon conducting, when decontroling button, A.C. contactor is still worked, and guarantees that motor runs well; When lacking arbitrary phase voltage, the non-inductive voltage of its this coil, this moment the AND circuit no-output, trigger voltage is zero, bidirectional triode thyristor cuts out, and cuts off the A.C. contactor power supply, thereby reaches the purpose that motor is not burnt.

Claims

1, a kind of being located between phase line and zero line is by fuse (RD ₄), A.C. contactor (C), normally closed button (TA), often drive button (QA); be unified into the contactless protective device of motor phase shortage of motor main control loop successively; it is characterized in that in the main control loop; connect a kind of switch element (TLC) and being provided with by getting the voltage that phase current induces is through controlling the control circuit of these element through and off with the gate logic computing circuit.

2, the contactless protective device of motor phase shortage according to claim 1 is characterized in that said switch element (TLC) is bidirectional triode thyristor or same function element.

3, the contactless protective device of motor phase shortage according to claim 1 is characterized in that said control circuit comprises:

Being used to detect the voltage that phase current induces provides signal for AND, then by induction coil (L _1-3), rectifier diode (D _1-3) and filter capacitor (C _1-3) testing circuit that constitutes;

In order to enlarge the contactless protective circuit scope of application of motor phase shortage, add voltage-stabiliser tube (D in the back of rectifier diode _5-7), when phase shortage for triode is ended fast, also will with filter capacitor (C _1-3) the suitable discharge resistance (R of its resistance in parallel _1-3), voltage-stabiliser tube, filter capacitor, discharge resistance parallel connection, an end ground connection, another termination rectifier diode positive pole and current-limiting resistance one end, and constitute and door three input circuits;

Being used to form AND is that switch element (TLC) provides control signal, by current-limiting resistance (R _4-6), biasing resistor (R _7-9), resistance (R ₁₀), triode (Q _1-3) constituting AND circuit, current-limiting resistance one end connects with diode cathode in this circuit, and the other end and biasing resistor one end are connected on the transistor base together, and biasing resistor other end ground connection, triode (Q _1-3) series connection each other, triode (Q ₃) emitter, promptly be connected to zero line again through resistance (R ₁₀) ground connection;

Be used to AND circuit that DC power supply is provided and set up trigger voltage for switch element, by transformer (T), rectifier diode (D ₄), filter capacitor (C _4-5), resistance (R ₁₁) form DC power supply, supply with switch element in order to obtain positive trigger voltage, and DC power supply is divided into two kinds of earthing methods, i.e. the public ground of transformer secondary coil one termination (G ₁), electric capacity (C _4-5) positive pole meets the public ground of branch (G ₂), the negative pole of its DC power supply and triode (Q ₁) collector electrode joins, and divides public ground to link with switch element (TLC) the control utmost point, that is to say that when the AND input all has signal, and output is from triode (Q ₃) emitter to dividing public ground, just can have trigger voltage to deliver to the control utmost point of bidirectional triode thyristor, the motor main control loop could operate as normal, when the AND input lacks arbitrary road signal, trigger voltage equals zero, and controllable silicon is closed at once, cuts off the whole power supplys of motor.