Procedure and method for checking the trip and re-closing failure of air circuit breaker(ACB)

Air circuit breaker（ACB) tripping, re-closing failed

1. First determine whether the Air circuit breaker is not accidentally tripped

Non-accidental trip means trip without short circuit or overload fault. There are many reasons for the Air circuit breaker not to close. First of all, it is necessary to determine the trip caused by short circuit and overload, or the air circuit breaker itself or the control loop is faulty. Find and determine whether the circuit is faulty or the air breaker itself is faulty.
After determining the fault of the air circuit breaker, draw out the circuit breaker (refers to the drawer type air circuit breaker) for inspection.

2. Universal type circuit breaker common trouble repair

(1) The circuit breaker cannot be closed due to the loss of power in the undervoltage tripping device. If the voltage is too low or the coil of the undervoltage tripping device is out of power, the circuit breaker will trip and cannot be re-closed. The following four conditions can cause the undervoltage tripper coil to lose power.

• (1) The protection circuit fuse is blown, such as RT14, resulting in circuit blockage and loss of power of tripping coil of undervoltage tripping device;
• (2) The close button, relay contact, circuit breaker auxiliary contact head bad contact, component damage, may lead to circuit blockage, tripping coil power loss;
• (3) The connection wire in the loop is broken, and the crimping screw is loose and loose, which will also lead to the circuit is blocked, and the tripping coil is disconnected;
• (4) Due to the coil of the undervoltage release is in the working state of electricity for a long time, environmental pollution and the armature is not flexible, or the air gap between the core and the armature is too large, it is easy to make the current too large and lead to the release coil heating and burning, lose the function of the release coil.
• The above fault through observation and simple inspection and test can make a correct judgment, so once found fault should be eliminated in time, such as loose contact to tighten, component damage and coil burn that needs to be replaced.

(2) Mechanical system failure, resulting in circuit breaker can not close.After tripping and closing the circuit breaker operating mechanism for many times, the mechanism is severely worn and the following faults may occur.

• (1) Motor transmission mechanism wear, such as ME switch worm gear, worm damage, can not drive the circuit breaker operating mechanism buckle, close. Worm gear, worm replacement is more complex, the need for professional maintenance.
• (2) free tripping mechanism wear, so that the circuit breaker is difficult to buckle, tripping easy, sometimes forced to buckle, in case of vibration, the trip; Sometimes after the buckle, a closed buckle will slip. At this time, the adjusting screw should be rotated to adjust the relative position of tripping half shaft and tripping buckle, so that the contact area is about 2.5mm2, and the corresponding parts should be replaced if necessary.
• (3)The energy storage spring of the operating mechanism is faulty. The breaking energy storage spring of the operating mechanism loosens or loses its elasticity after many stretches, and the closing force becomes smaller. When closing, the four-bar mechanism of the circuit breaker cannot be pushed to the dead point position, and the mechanism cannot keep itself in the closing position. Therefore, the circuit breaker cannot be closed normally. The storage spring must be replaced.
•  (4)The operating mechanism is not flexible, and there is a stuck phenomenon. Because this kind of circuit breaker is not fully enclosed, if the screws, nuts and other foreign bodies are accidentally left in the operating mechanism, so that the circuit breaker operation stuck phenomenon, will affect the closing; In addition, the rotation and sliding parts lack of lubricating grease, the opening energy storage spring of the operating mechanism is slightly deformed, and the circuit breaker can not close the brake. Therefore, when the above failure occurs, in addition to checking the operating mechanism, there is no difference, but also to inject lubricating grease into the rotation and sliding part.