What is the problem if the start stop start line and the power line of the contactor control motor a

Each signal is described separately;

A running signal is sometimes designed to stop a signal, but a run signal that is inverted in the DCS logic is a stop signal. This signal is connected to the auxiliary contact of the contactor (KM2 above), which is usually connected to the normally open contact. The contactor coil is energized, the normally open contact is closed, and the DCS obtains this signal state.

DCS test and connect DI module channels.

long-range signals; This signal is connected to the DCS by the contact of the transfer switch on the low-voltage electrical control cabinet, the general low-voltage electrical control cabinet is equipped with remote control and local control, the transfer switch is remote, and the DCS can start and stop the motor operation only after receiving this DI signal. DCS test and connect DI module channels.

fault signals; When the simple contactor motor starts, the thermal relay is generally connected to the fault signal (FR in the figure above) for overcurrent protection. This is one of the contacts of the FR thermal relay in the picture above. In addition to the thermal relay, there are two other situations in which the fault signal is connected:

1.When connected to the motor protector, the detection range is more, overload, short circuit, loss of voltage, three-phase balance and so on. 2.

Connected to the inverter fault output. A good inverter function is much more powerful than the comprehensive protection, including all the comprehensive protection functions, and with torque detection, its own circuit detection, etc., the output fault signal. Of course, the latter two cases are not a description of the problem.

DCS test to DI module channel for fault signals.

start-up signal; The output relay contact (generally normally open) of the DO module of the DCS is connected to the coil terminal block of the contactor, as shown in the figure above DCS starts.

stop signal; The output relay contact (generally normally closed) of the DO module of the DCS is connected in series to the coil terminal of the contactor, as shown in the figure above.

Of course, the internal wiring of these components of the low-voltage electrical control cabinet has been connected, and the terminal blocks have been reserved for the DCS signal. That is to say, all signals of the DCS can be connected to the terminal blocks in the low-voltage electrical cabinet according to the wiring diagram.

Pure hand hitting, hope. In addition, I have been engaged in DCS debugging work for 11 years, and I am familiar with Hollysys, Zhejiang University, Xinhua, ABB, Siemens and other brands DCS.

It would be nice to swap the wires, what could be the problem?

In addition to the wiring error, it is the button contact or AC contactor contact that cannot be released in time.

It's hard to say this, this is the control wiring, and the primary wiring is the incoming and outgoing wires on the contactor.

If the coil is disconnected within a few seconds after power-off, it is that the core of the AC contactor is magnetized, and it is good to remove the core and return the magnetism to install it back, if it has not been disconnected for a long time: first, the iron core is stuck, remove it and check it to see where it is stuck, and repair it where it is stuck, and second, the contact current is too large, and it may be welded together, so change one.

The AC contactor is sticky. The following factors are considered for reference;

1. Check whether there is metal slag falling into the auxiliary contact of the main contactor.

2. The frequency of advance and retreat is too high.

3. Melt between two or three dynamic and static points of the main contact.

4. The wire pack cannot be reset after power loss.

AC contactor contact adhesion (can not separate by itself), to see the degree of damage to the contact, not too bad can be taken to use No. 0 fine sand skin polishing, and finally with a new 100 yuan repeatedly back and forth grinding the contact plane, to smooth and smooth.

The contacts of the AC contactor are sticky, to see the degree of damage to the contacts, if it is not too bad, you can take the No. 0 fine sand skin to polish, and check whether the internal spring of the AC contactor is broken.

This diagram is a bit flawed, and the control line is not independent fu.

The problems are as follows.

1.Control the internal resistance of the line itself.

2。Short circuit inside contactor and thermal relay.

3。The output line is short-circuited.

In fact, the maintenance is very simple, and the motor wire is removed first.

It is only necessary to disconnect the relevant line and measure the resistance of the breaking line, and the interphase resistance should not be less than 1m.

According to your electrical circuit diagram, after the forward rotation starts, it cannot be reversed directly, it is necessary to press the emergency stop, and then reverse, if you want to direct control the forward and reverse rotation, you also need to add a mechanical interlock, only the electrical interlock is not safe, it is easy to short circuit, in addition, your electrical circuit diagram does not have short circuit protection, that is, the fuse, fu

It should be that the quality of the contactor is not good. One of the six main contacts is sticky, and if it happens to be in the commutation circuit, the other contactor will be short-circuited as soon as it is engaged.

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