Tag: troubleshooting

Safety relay is the main component of electric locomotive control circuit and monitoring protection system. When the electrical components or connection wires in the main circuit or auxiliary circuit break as the electric locomotive is running, the safety relay of corresponding monitoring protection system can transfer the fault into electric signal. On one hand, the electric signal will be fed back to the opening coil of main breaker to trip the main breaker, thus cutting off general power supply of the electric locomotive to protect it. On the other hand, the electric signal will be fed back to signal device (including mechanical signal and electrical signal) and make it to display different fault conditions, thus guiding the electric locomotive conductor to deal with faults timely and correctly. In this respect, the safety relay doesn't directly control the main circuit or auxiliary circuit, but it's of great importance to the electric locomotive.

Common fault for the iron core of an AC contactor is about the large noise. If it's caused by insufficient coil voltage after inspection, adjust the power voltage. If it's caused by bad contact between contact surfaces of dynamic and static cores, make contact surfaces smooth to ensure a good contact. If the noise is caused by the break of short circuit ring, replace or weld the short circuit ring. Another common fault is that the armature doesn't fall when powering off. This may be caused by small spring pressure between contacts, adjust the contact force please. If it's caused by block of armature or mechanical part, remover the barrier. There should be a clearance of 0.1～0.2mm in the central pillar of E-shaped core, if the clearance disappears due to iron core wear, the iron core may be stuck, repair the central pillar plane of the E-shaped core.

Safety light curtain is a powerful safety laser sensor for machine guarding and personal safety. It is rather convenient and flexible in wiring and installation. The safety light curtain is equipped with flexible and relevant software, which can easily change the shielding and blanking effect according to the customers' various on-site requirements. It greatly reduces the time for re-arrangement and re-wiring. However, due to the complexity of the production process, the on-site product models often change, the settings for the safety light curtain also change accordingly. There are still some common problems in installation and maintenance. Today, ATO will tell you how to solve these problems.

Side blow of static contact and moving contact knife in closing
The fault cause is that the inappropriate position of static contact and moving contact knife causes side blow in closing. Check whether the fastening screw of moving contact knife of disconnect switch is too loose or too tight. Check whether the split ring on both sides of static contact of fuse type disconnect switch has movement or deforms or is damaged owing to poor contact, overheating or annealing.
Solution: adjust the degree of tightness and position between blades of fastening screw of level 3 moving contact, adjust the degree of tightness of moving contact knife, adjust moving contact knife to the center between moving contact knife and static contact, no side blow in closing test, no jam in closing. Fuse type disconnect switch adjusts the split ring on both sides of static contact to put the gap between static contacts at the center line of blades of moving contact knife. Then, conduct closing test.

There should be no open circuit on the secondary side of the current transformer in operation. Once the open circuit occurs on the secondary side, high temperature caused by excessive iron loss may burn out the current transformer or enhance the voltage of secondary winding, thus breaking down the insulation and leading to the danger of high voltage electric shock. Therefore, when replacing a meter such as an ammeter, active power meter and reactive power meter, please ensure the current circuit in short circuit before operation. After replacement, connect the meter in the secondary circuit and then remove the short-circuit wires while checking if the meter is normal. In case sparks appear when removing the short-circuit wires, that means the current transformer disconnects, please short the loop again and confirm the meter loop isn’t an open circuit. When removing the short-circuit wires of the current transformer, please stand on an insulated pad and consider a protector to stop the current transformer loop. When it finishes work, the protector can be put in use.

There's no display on the panel after the UPS starts, UPS doesn't work?
Fault analysis: the fault may lie in power input, battery and power detection, battery voltage test circuit:

1. Check if the power input fuse is burned out.
2. If the fuse works normally, check whether the battery fuse is burned out, because some uninterruptible power supply may close all outputs and display when it can't detect a voltage.
3. If the battery fuse is complete, please check if the power detection circuit works normally. If it doesn't work normally while UPS can't start without power supply, UPS will also close all outputs and display.
4. If the power detection circuit works normally, please check if the battery voltage test circuit is normal.

There is no signal waveform on the screen when collecting signals?
1. Check whether the detector is normally connected to the signal wire.
2. Check whether the signal wire is normally connected to the BNC (namely channel connector).
3. Check whether the detector is normally connected with the object under measurement.
4. Check whether the object under measurement produces a signal (Signal channel can be connected with the fault channel to find out the fault).
5. Collect the signal again.
6. Check the state of the trigger mode.

Solenoid valve is a basic component of automation to control the fluid, which widely applied both in the industry and in our daily life. Now and then, this small valve encounters some problems, which further affects the normal operation of the whole equipment. So, it would be better to learn some common problems of solenoid valve and know how to trouble shoot them. Here are some common problems occurring with solenoid valves for your reference.

• Solenoid valve doesn’t work after energized.
• The valve cannot be closed.
• There is a leakage inside or outside the solenoid valve.
• There is a noise after the valve power on.

Troubles with the induction motors are generally divided into two categories. One is the electrical faults, such as the various faults of switches, buttons, fuses, electric brushes, stator winding, rotor, starting equipment and so on. The other is the mechanical problems, such as the problems of the bearing, fan blade, motor frame, coupling, end bell, bearing cover, spindle and so on.
Once the induction motor has any problem, there might be some abnormal phenomena, for instance, the rising temperature, over current, vibration and abnormal noise and so on. Therefore, learn about these phenomena, find out the cause, and then troubleshoot it. The following is some common faults and troubleshooting method of three-phase induction motors for your reference.

Short circuit of the contactor
Possible causes of the fault:

• The contactor works in the environment of damp, dust, steam, or corrosive gases.
• The arc chute damages or falls, load short leads to the contact short of the contactor.
• Incorrect operation of the positive and reverse contactor, as well as unreliable interlocking, make two contactors to pull in at a same time when reversing.

Maintenance method:

1. Improve the working environment and keep clean.
2. Match an arc-extinguishing equipment again.
3. Handle the load short failure.
4. Recheck the contactor's interlocking circuit, change the operation mode.

When switching power supply blows a fuse, when there is no DC output or volatge output is unstable, when switching power supply has poor load capacity, how to do? Click it and then you will know how to deal with these problems as well as some repairing skills.

Servo driver is a kind of controller used to control the servo motor, which belongs to the servo system. When some problems accur as follow of a servo drive, how we should test and repair? Here are 6 tips  to maintain a servo drive.

Stepper motors are now widely used in the industrial areas, but from time to time some problems with stepper motors occurs as follows. Aimed to these problems, there are some troubleshooting for your reference.

1. How to control the direction of stepper motor?
2. When stepper motor generates vibration and noise, how to do it?
3. Why the stepper motor doesn’t rotate or move back and forth after it is powered?
4. Why the torque of stepper motor is decreasing with the rise in rotational velocity?
5. Why stepper motor can run normally at low velocity, but can’t start at certain higher velocity with some noise of whistler?
6. How to prevent the power interference of stepper motor?

Stepper motor is an open-loop control motor which transforms electric pulse signal into angular displacement or linear displacement.  However, there are some errors occuring between the actual angle stepper motor rotates and the theoretical step distance. There are some certain errors from one step to any other step, but the step number of each cycle of the stepper motor is the same. In the case of no step loss, the step error is not accumulated for a long time.
How to prevent step loss with stepper motor as the above mentioned? First of all, we need to know why stepper motor losses step?

1. The rotor acceleration is slower than the rotating magnetic field of the stepper motor.
2. The average speed of the rotor is higher than the average rotating speed of the stator magnetic field.
3. The load inertia of stepper motor is large.
4. The stepper motor produces the resonance.

1. Servo motor does not run when the pulse is output, how to solve the problem?

1. Monitor the current pulse output value of controller and check if pulse output indicator lamp flashes to confirm 
   that the controller has performed command pulse and has output pulse normally.
2. Check if the control cable, power cable, encoder cable between controller and driver are matched incorrectly damaged or contacted poorly.
3. Check if the brake of servo motor equipped with brake has been turned on.
4. Monitor the panel of servo driver to confirm if the pulse command has been input.
5. Run command is normal.
6. For control mode, always choose position control mode.
7. Check if the type of input pulse set by servo driver matches with that of command pulse.
8. Ensure that positive side drive prohibition, negative side drive prohibition signals and deviation counter reset 
   signal are not input and the servo motor runs normally if load is removed, then check the mechanical system.

As the executive element of mechanical equipment, servo motor is used widely in servo system. When using servo motor, there is a phonomena of overheating when working. As you are not familiar with the principle and structure of servo motor, how to judge whether the heating value is normal or not? And how to reduce the heating value of servo motor?

One of the most significant advantages of stepper motor is that it can be controlled accurately in open loop system because the rotor position can be determined only by tracking the input step pulse, but overheating problem occurs easily in stepper motor, so how to solve this problem if such condition occurs?