CN2280382Y

CN2280382Y - Multi-protection, energy saving starter for ac motor

Info

Publication number: CN2280382Y
Application number: CN 96247620
Authority: CN
Inventors: 张正刚
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-11-25
Filing date: 1996-11-25
Publication date: 1998-04-29
Anticipated expiration: 2006-11-25

Abstract

The utility model relates to a multi-protection energy saving starter for AC motors. The utility model is characterized in that self-healing low-voltage capacitors are separately bridged between every two phases of the three-phase power supply of the motor, and any phase wire of the three-phase power supply is led out to another phase wire in one way through a coil for an interrupted protection relay and a heating relay and to other phase wires in other way through a coil for a protecting electric appliance and the normally open contact of an interrupted relay; moreover, the normally open contacts of the protection relay are separately connected in series to each phase wires of the motor power supply. The utility model can effectively control or prevent wattle sselectric power from flowing back and forth on high-low voltage electric network, having obvious power saving, and the utility model simultaneously has various protective functions of over current, short circuit, phase failure, etc. and can carry out a series of effective protection when the AC motor is started up, braked or normally operated.

Description

Alternating current motor is protected the economize on electricity starter more

The utility model relates to the starting drive of alternating current motor.More particularly, be a kind of economize on electricity starter that has multiple electric motor protecting function simultaneously.

At present, state's built-in motor power consumption accounts for 55%～60% of national power consumption, and the operational efficiency of China's motor itself on average is lower than advanced country 20%～25%, and as seen, power wastage is very big.Though many experts carry out the energy-conservation of consumption reduction measure from optimal design technology, choose reasonable, economical operation, technological transformation aspects to motor, and the starting energy consumption of asynchronous motor and consumption reduction approach thereof are still generally out in the cold.Alternating current motor is beginning to start moment, when the rotor of induction motor still remains static, its power factor is low to reach 10%, it is much bigger that low like this power factor will make motor and its duty ratio start the electric current that needs when quickening under High Power Factor, can reach 5～6 times of full-load current sometimes.Big starting current also may make line voltage play pendulum, thereby influence is to the power supply quality of other power consumption equipment.

The purpose of this utility model is to avoid above-mentioned weak point of the prior art, provides a kind of alternating current motor to protect the economize on electricity starter more.To control or to avoid idle the flowing back and forth on the high-low pressure electrical network of electric power, saves energy, the nervous situation of alleviation electricity supply and demand.Simultaneously, can carry out effective electric motor protecting to faults such as the phase failure, overcurrent and short circuits.

The purpose of this utility model is achieved through the following technical solutions.

A, alternate, cross-over connection self-healing low-voltage capacitance C1, C2 and C3 respectively at motor three-phase power (A, B, C) per two;

B, from arbitrary phase line (B) of described three phase mains, 2RDb draws by current-limiting resistance, one the tunnel through interrupting relay ZJ coil, thermal relay RJ to another phase line (C), another road through protection relay coil CJ and the normally opened contact that interrupts relay ZJ to other phase line (A); And there are protection relay CJ normally opened contact CJ-1, CJ-2 and CJ-3 to be serially connected in respectively on each phase line of motor power.

The utility model is to adopt self-healing low voltage power capacitor to be connected in parallel on the motor winding, make the required reactive power of motor directly carry out the electromagnetic energy conversion by capacitor, minimizing is shoved to the influence of electric power system because of startup, and starting current also just is subjected to certain limitation.Compared with the prior art, the utility model can reduce the load current of power supply network, distribution transformer and low-voltage distributing line, reduce the conductor cross-section of distribution line and the capacity of enterprise's distribution transformer, reduce the power loss and the electric energy loss of power distribution network, the working voltage of the motor at working voltage place on the low side is improved, the idle economic equivalent of operating point is big, thus fall decrease effective.

By the starting current of power distribution network, improve the functional reliability of control appliance when the utility model can reduce motor start-up, and prolong the useful life of switch, control appliance.In addition, the utility model can carry out effective electric motor protecting to faults such as phase failure overcurrent and short circuits owing to be provided with multifunctional protection circuit simultaneously.

Accompanying drawing is the utility model circuit theory diagrams.

By the following examples, in conjunction with the accompanying drawings, the utility model is further described.

Embodiment:

Referring to accompanying drawing,

Per two alternate at motor three-phase power A, B, C, cross-over connection self-healing low-voltage capacitance C1, C2 and C3 respectively;

From arbitrary phase line B of three phase mains, 2RDb draws by current-limiting resistance, and one the tunnel through interrupting relay ZJ coil, thermal relay RJ to another phase line C, another road through protection relay coil CJ and the normally opened contact that interrupts relay ZJ to other phase line A; And there are protection relay CJ normally opened contact CJ-1, CJ-2 and CJ-3 to be serially connected in respectively on each phase line of motor power.

As shown in the figure, with protection relay CJ coil is connected in series stop botton TA and start button QA arranged, and self-holding contact CJ-4 is often opened in parallel connection on start button QA.

In the present embodiment, the mistake, the undervoltage warning circuit that are made of comparator A1, A2, luminous tube D4, D7 and D8 and switch transistor T 1 are set simultaneously, the threshold voltage of described comparator A1, A2 is from the output of three terminal regulator IC1, and the line voltage of three phase mains is taken from the input of three terminal regulator IC1.

Start the Capacity Selection of capacitor C1, C2 and C3, can carry out according to the requirement of different degree of compensation.Usually, start capacitor volume select to satisfy following two condition: a, when stationary rotor, the terminal voltage of motor should be about 80% of rated voltage; B, when motor almost reaches rated speed, the terminal voltage of motor should be 100% of rated voltage.Starting capacitor volume can calculate according to following formula: Qq=(0.5～0.25) * motor rated capacity.

The circuit working principle is as follows:

One, start-up control loop:

A, B, C three phase mains-mains switch HK-fuse 1RD-capacitor group put into operation, and simultaneously ,-2RDb-interruption relay ZJ gets electric-thermal relay RJ-C phase power supply.

A phase power supply-stop button TA-starting button QA (at this moment; normally opened contact C-4 self-locking)-interruption relay ZJ normally opened contact---protection relay CJ coil gets electric (normally opened contact CJ-1, CJ-2 and CJ-3 connect, the running of motor total head)-fuse 2RDb-B phase power supply.

Two, overcurrent protection control loop.

B phase power supply-fuse 2RDb-interruption relay ZJ coil-thermal relay contact (during as overcurrent, release is opened automatically, and motor promptly stops)-C phase power supply.

Three, open phase protection control.

When the phase failure of A phase, the CJ coil losing electricity, main contacts CJ-1, CJ-2 and CJ-3 disconnect, and motor is out of service.When the B phase or the phase failure of C phase, the ZJ coil losing electricity, its contact disconnects, and causes the CJ coil losing electricity, and motor is shut down.

Four, excessively undervoltage warning.

The B point connects B phase power supply, the N connecting to neutral, on resistance R 1 and potentiometer P1, produce voltage drop, 15V burning voltage by resistance R 2, capacitor C 4, C5, diode D1, D2 generation, through R5, R6 and R7 dividing potential drop,, and in comparator A1, A2, compare with the sampling voltage of electric main for comparator A1, A2 provide threshold voltage.When electric main was lower than rated voltage 10%, Yellow luminous pipe D7 conducting was luminous; When electric main was higher than rated voltage 6%, red luminotron D8 conducting was luminous, under the normal condition, and triode T1 conducting, thereby by the luminous indication of green luminotron D4 " working properly ".

Present embodiment be by fuse 1RD to motor, capacitor and protection, control circuit when being short-circuited fault, the quick-break fuse reaches the purpose of short-circuit protection.In addition, when motor is shut down, utilize A.C. contactor CJ that motor and capacitor are separated, itself or motor are moving to cause damage to installing can to prevent the self-excitation overvoltage.

Claims

1, a kind of alternating current motor is protected the economize on electricity starter more, it is characterized in that:

2, alternating current motor according to claim 1 is protected the economize on electricity starter more, it is characterized in that, with protection relay CJ coil is connected in series stop botton TA and start button QA arranged, and self-holding contact CJ-4 is often opened in parallel connection on start button QA.

3, alternating current motor according to claim 1 and 2 is protected the economize on electricity starter more; it is characterized in that; mistake, undervoltage warning circuit that setting is made of comparator A1, A2, luminous tube D4, D7 and D8 and switch transistor T 1; the threshold voltage of described comparator A1, A2 is from the output of three terminal regulator IC1, and the line voltage of three phase mains is taken from the input of three terminal regulator IC1.