[Inverter Knowledge] 380V 220V AC Contactor Wiring Detailed Illustrations

[Inverter Knowledge] 380V 220V AC Contactor Wiring Detailed Illustrations
Conai Escalator from 2017-06-20
[Inverter Knowledge] 380V 220V AC Contactor Wiring Detailed Illustrations
 
1, AC contactor in the motor direct start circuit applications
Direct start is the most basic low-voltage motor start mode, a wide range of applications, general small and medium enterprises and rural agricultural and sideline products processing use this start mode. The so-called low-voltage motor. Usually refers to the rated voltage of 380V or 660V asynchronous motor. Power 22kW and below the motor can be used directly to start the way, the use of AC contactor for the main switch, is not recommended to use plastic cover switch closing start. So that the safety is poor, there have been arc burning accident.
The motor is directly activated by the primary circuit and the secondary circuit, respectively, see Figure l and Figure 2.
 
figure 1:
 
Figure 2:
The so-called circuit is the motor winding current through the circuit components and wires: secondary circuit is to ensure the normal operation of the equipment indispensable auxiliary circuit. The main functions of the secondary circuit are control, measurement, signal and protection. So that the motor start and stop the operation of the circuit is the secondary circuit control function circuit; voltage, current, power and power factor measurement of electrical parameters such as its measurement function; run and stop the light, abnormal alarm sound is the second Signal circuit circuit components: thermal relay, motor protection and other components can achieve motor protection. The following specific analysis of the motor directly start the circuit work process.
In Fig. 1, the line of fire (phase) Ll, L2 and L3 of the three-phase power supply is connected to the upper end of the isolation knife switch QS. The QS function is to disconnect the power supply during overhaul. So that the maintenance circuit and the power supply has a clear disconnect between the point to ensure the safety of maintenance personnel. FU is a fuse for protection of a circuit. When starting the motor, first turn on the knife switch QS, and then if the AC contactor KM main contact is closed, the motor is energized: the contactor main contact is disconnected and the motor stops running. Contactor contact closed or not. It is controlled by secondary circuit.
Figure 2. FUl and FU2 are secondary fuses. SBl is the stop button. SB2 is the start button. FH is the protection output contact of the thermal relay. Press SB2. AC contactor KMl coil was energized, its main contact closed, the motor began to run. At the same time, the auxiliary contact KM1-1 of the contactor is also closed. It allows the contactor coil to obtain a continuous working power, contactor to take the state to stay. It is customary to use the auxiliary contact KMl-1 as the self-protection (holding) contact.
The motor is running. If there are over-current or short circuit and other abnormal circumstances, the thermal relay FH (see Figure 1) within the bimetal will be due to excessive current and thermal deformation, within a certain period of time to protect the contact FH (see Figure 2) action Disconnected, causing the contactor coil to lose power, the contactor main contact is disconnected, the motor stops running, protects the motor from being overcurrented. After the protection action, the contactor KM1-1 of the contactor is disconnected and the motor remains in the outage state.
If the motor is running, press SBl. The motor will also stop running, the action process and thermal protection of the same action.
Stop indication green light HG and running indicator red light HR is controlled by the normally closed (dynamic) or normally open (moving) auxiliary contacts KMl-2, KM1-3 of the contactor, respectively. Current transformer TA secondary coil series ammeter PA, voltmeter PV is directly connected to the power line, they are running on the motor current and voltage.
Figure 2 in the wire "ding" shaped place where no "·" can also be. There is no "·" in electrical drawings. In fact, where the dots or not, are in line with GB GB47 "electrical diagram with graphic symbols" requirements, but in different applications have their own drawing habits only.
2, the motor reversible operation control circuit
In order to make the motor can forward and reverse, can be used two contactor KM1, KM2 switch motor three-phase power phase sequence, but the two contactors can not pull, if the same will cause the power supply short circuit accident, in order to To prevent such accidents, in the circuit should take a reliable interlock, the picture shows the use of buttons and contactors double interlock of the motor is positive and negative operation of the control circuit.
The line analysis is as follows:
First, the positive start:
1, close the air switch QF connected to the three-phase power supply
2, press the forward start button SB3, KM1 power suction and self-locking, the main contact closed to turn on the motor, the motor phase sequence is L1, L2, L3, that is running forward.
Second, reverse start:
1, close the air switch QF connected to the three-phase power supply
2, press the reverse start button SB2, KM2 power suction and through the auxiliary contact self-locking, normally open the main contact closed with the motor three-phase power phase sequence, then the motor phase sequence is L3, L2, L1 , That is, reverse run.
Third, the interlocking link: with a prohibited function in the line from the security role
1, contactor interlock: KM1 coil loop into the KM2 normally closed auxiliary contact, KM2 coil loop into the KM1 normally closed contact. When the positive contact contact KM1 coil power action, KM1 auxiliary normally closed contact disconnect the KM2 coil circuit, if KM1 get electric pull, you must first make KM2 power release, the auxiliary normally closed contact reset, which To prevent the KM1, KM2 at the same time caused by inter-phase short circuit, this line is called interlocking links.
2, button interlock: In the circuit using the control button operation of the positive and negative control circuit, buttons SB2, SB3 have a pair of normally open contacts, a pair of normally closed contacts, the two contacts were KM1, KM2 coil loop connection. For example, the normally open contact of the button SB2 is in series with the contactor KM2 coil, and the normally closed contact is in series with the contactor KM1 coil circuit. The normally open contact of the push button SB3 is connected in series with the contactor KM1 coil, while the normally closed contact voltage KM2 coil circuit is connected in series. So when you press the SB2 can only have the contactor KM2 coil can be powered and KM1 power, press SB3 when only the contactor KM1 coil can be powered and KM2 power, if both press SB2 and SB3 two The contactor coil can not be energized. This has played a role in the interlock.
Fourth, the motor forward (or reverse) after the start of operation, do not have to press the stop button to stop the motor, you can directly press the reverse (or forward) button to make the motor in the opposite direction.
Fifth, the motor overload protection by the thermal relay FR completed.
Schematic diagram of reversible operation control wiring of motor
Debugging of Motor Reversible Operation Control Circuit
1, check the main return road wiring is correct, in order to ensure that the two contactor action can be a reliable exchange of the motor phase sequence, the wiring should be connected to the upper end of the contact line in the contactor under the mouth phase modulation.
2, check the wiring is correct, the power test, power test to prevent accidents, should first disconnect the motor wiring.
Symptom Preprocessing:
1, do not start; one of the reasons, check the control insurance FU is broken, the thermal relay FR contact is wrong or bad contact, SB1 button normally closed contact is bad. Cause of the second button interlocking wiring is wrong.
2, the starting contactor "han" do not suck; this is because the contactor normally closed contact interlocking wiring is wrong, the interlocking contact has become their own lock themselves, and start the closed contact is the contact The contactor is closed, the contactor coil and power release, the release of the normally closed contact with the contactor and then pull, contact and disconnect, so there will be " Da "contactor does not pull the phenomenon.
3, can not lock a lift contactor to disconnect, this is because the self-locking contact wiring is wrong.
 
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