Try to analyze the reason why the main contactor of the crane does not suck

The main reasons for not engaging are the control end break, no call, poor grounding of the control end and control coil breakage.

Relay (also known as contactor) is a kind of electrical control device, which is an electrical appliance that makes a predetermined step change of the controlled quantity in the electrical output circuit when the change of the input quantity reaches the specified requirements. It has an interactive relationship between the control system (also known as the input loop) and the controlled system (also known as the output loop). Usually used in the control circuit of automation, it is actually a kind of "automatic switch" that uses a small current to control the operation of a large current.

For the above fault causes, they can be measured or tested by the voltage range, diode level and resistance file of the multimeter to determine which fault is it.

Check the main power supply voltage, whether there is a lack of phase, if the lack of phase check the incoming line, the current collector is usually called the slider, cart, trolley, whether the main order of the auxiliary hook is in the zero position, whether the emergency switch is closed, whether the limit of each bin door is in the closed position, whether the stop button is normal, whether the overcurrent is normal. These can be seen on the schematic. If the overcurrent, the bin door limit, the stop button is no problem, the main contact can be engaged with kicking, of course, the premise is that the contactor coil is normal, the control power supply is normal, and there is a situation that the trolley or cart limit is bad, and at this time, the zero contact of the trolley or cart is also broken, which can also cause the main power supply not to self-lock.

It's easier said than done, but it's still a bit of a hassle to actually check.

1. There may be no electricity, but it is not that there will be electricity when the brake is closed (such as lack of phase).

2. The control line is disconnected, and the main contactor coil shall not be powered or working (or the protection circuit will be activated, such as phase sequence protection, overcurrent protection, etc.).

3. The contactor coil burns out, energized but does not work.

Check whether the zero contactor coil is burned out, check whether the doors are closed, if the contact of the limit switch can not be closed every time the limit switch is closed, the main contactor coil can not be engaged without voltage, check whether the normal closed contact of the overcurrent relay of each motor is in good contact, check whether the limit switch of the cart, trolley and small hook is good, whether the four cams are in the zero position, whether the contact is good, if not, it may be that the zero protection control loop is broken, I hope it can help you!

The door switch is not closed, the controller does not return to the zero position, the contactor is damaged, and the contactor coil circuit is open

Check whether the wiring of the main contactor control loop is loose or the crimping head is falling off? Is the power switch of the control loop closed? Is the protection of the control loop (e.g. fuse or air open) blown or tripped?

Protection of each zero position and overcurrent relay contacts as well as phase loss.

The undervoltage causes the contactor to not engage, and the mechanical control protection is disconnected.

The phase sequence is not reversed, because the main AC contactor of the total power supply is controlled by the phase sequence protector, and the main protection is caused by the reversal of the phase sequence, which causes the crane to cause accidents due to control errors.

The contactor line is broken and the contactor is old. Contact points burned. There is a problem with the coil inside the contactor. It depends!

The control line may not be connected correctly, use a screwdriver to directly push down the descending contactor, see if the crane has action, if there is action, the interlocking wire is connected wrong.

The control line is broken or the limit switch is in trouble.

1. Because the power supply voltage of the control loop is lower than the rated voltage of 85, the electromagnetic force generated by the electromagnetic coil after powering on is small, and the moving iron core cannot be quickly sucked to the static iron core, resulting in the contactor being slow or not tight, and the power supply voltage of the control loop should be adjusted to the rated working voltage.

2. The spring pressure is insufficient, resulting in abnormal contactor suction; The reaction force of the spring is too large, resulting in slow sucking, and the contact spring pressure overtravel is too large, so that the iron core can not be completely closed; The spring pressure and release pressure of the contact are too high, so that the contact cannot be completely closed. The solution is to adjust the spring pressure appropriately and replace the spring if necessary.

3. Due to the large gap between the moving and static cores, the movable part is stuck, and the rotating shaft is rusted or deformed, resulting in abnormal contactor sucking. During processing, the dynamic and static iron core can be removed for inspection, the gap can be reduced, the shaft and support rod can be cleaned, and the accessories can be replaced if necessary.

What is the reason why the AC contactor does not engage.

Check what the voltage of your contactor coil is, and then see if it's AC or DC, don't get it wrong. If all of the above are correct, it means that the coil is broken, and measure it with the resistance level of the multimeter.

1.The contactor should generally also have a start switch or button, whether it has been operated;

2.The contactor coil can be measured with a multimeter, the general DC resistance of the AC contactor is very small, but it should not be 0, if it is too large, or even to infinity, it is the coil burned;

3.Is its overload protection working? Some protections require manual reset.

4.Is there a similar lack of phase that causes the protective action?

5.The three air compressors work in parallel, which should be started with a pressure switch, and whether the pressure switch is checked for the line? It can be considered as a short circuit (equivalent to contact closing) and try it.

The power supply, main contactor, safety door, and operating handle of the overhead crane are normal, but the contactor does not engage when the start button is pressed? The main contactor was forcibly started with a change cone, and it was running normally!

Because on the starter coil (control loop), there are many (protective) limit switches connected in series! As long as one of them is not in contact or malfunctions, it will cause the contactor to not engage when the start button is pressed, and the main contactor will be forcibly started with a change cone, and it can run! Check the limit switches!!

Whether the control loop is fused or the disconnection contact is poor, and then see if there is no protection action after the final return (such as limit switches, etc.).

Do you judge the coil, or the button problem!

B+D is possible! Eliminate them one by one!

Cam controller SA1 SA3 circuit grounding reason.

The main hook generally has more problems, the motor is loud, but listening to the sound can not tell whether it is the motor or the reducer, at this time you should check the stator, whether the rotor is missing phase, whether the wiring is missing phase, if there is no problem at one time, check the contact closure and wiring of the cut resistor contactor.

The main hook does not move. The general control power supply is connected from the main power line, you can pull down the first empty opening, try the second control, observe whether the contactor action is normal, and often the coil wiring is broken, this article mainly takes the CJ12 contactor as an example The common wire is broken, the contact of the cam controller is not closed well, and the wire is broken.

Whether the zero relay is closed, for the time being, when the main order is in the zero position, there will be a relay in the pick-up state, and the overcurrent is not a problem.

The main hook does not rise, check whether the ascending contactor is engaged in the overload controller auxiliary point is moving, whether the rising limit is moving, and the descending contactor auxiliary point is closed, which can be seen on the schematic diagram.

If the speed is slow, check whether the cutting resistor contactor operates accordingly, generally the contactor auxiliary contact and the time relay are easy to have problems, and check whether the brake is open. Generally, check the overhead crane fault, first confirm whether the power supply voltage is normal.

Cam controller clamps, sinks, and checks the positioning wheels, positioning rods, bushings, and positioning teeth.

With contactor control, the cam controller contacts are still not easy to wear.

It is necessary to always check whether the motor slip ring is smooth, not too much dust, whether the wiring of the control panel is loose, if the wiring is oxidized, the wire nose should be replaced as soon as possible and crimped, the contactor should arrange time to check the contact, the moving iron core is loose, and the bracket gasket after the moving core falls and is easy to cause the coil to burn out.

The corners of the trunking and the places that are easy to be stepped on are the most likely to cause wire breakage and grounding, and there are many that seem to be connected and not connected, which makes it very difficult for you to find faults.

There are many more, so I won't be verbose here, and we will learn together if there are problems.

Frequent inspections and spot checks can be a good way to avoid many accidents.