Services and Support

Services and Support

Our company offers end-to-end, one-on-one customer service—from consultation and order placement to installation—ensuring that any issues are promptly resolved for you.

CM3 Series Molded Case Circuit Breakers

Fault Description Possible causes Troubleshooting
The circuit breaker is used for motor protection; it trips during the starting process, resulting in a failed start. 1) If the motor is started directly, the starting current is at least eight times the rated operating current, and may even exceed ten times. If the instantaneous overcurrent protection setting multiplier is improperly selected, the circuit breaker will trip during startup, preventing the motor from completing its start-up sequence.

1) Is the connected load a motor that requires direct-on-line starting, and what is its starting current?

2) Appropriately determine the circuit breaker’s rated current and the multiple of the instantaneous trip setting.

2) If the distribution cabinet is located far from the equipment, resulting in significant line voltage drop, the motor terminal voltage will fall below its rated voltage, causing the starting current to increase and triggering a trip.

1) Determine the motor terminal voltage (P = IUcos Φ);

2) Appropriately determine the circuit breaker’s rated current and the multiple of the instantaneous trip setting current.

3) If the motor is started under load, verify that the load is operating normally. Any signs of stalling or abnormal noises in the mechanical components can lead to poor operation, resulting in difficult starting, a sudden surge in current, and excessively long start-up times, which may trigger a trip. Additionally, equipment such as pumps and conveyors, when started under load, may trip if the start-up duration exceeds the allowable limit.

1) Inspect the mechanical condition of the motor (and its load).

2) Appropriately determine the circuit breaker’s rated current and the multiple of the instantaneous trip setting current.

During operation, the circuit breaker occasionally trips. 1) Overload tripping caused by three-phase load imbalance. 1) Determine whether the three-phase currents are relatively balanced.
2) If the cross-section of the connecting cable or copper busbar is too small, it can overheat, causing the circuit breaker to trip.

1) Determine the cross-sectional area and length of the connecting cable or copper busbar.

2) Select the appropriate cross-sectional area of connecting cables or busbars according to the sample specifications.

3) Select the appropriate length of connecting cables or busbars.

3) If the connecting screws are not tightened or there is poor contact, the contact resistance will increase, leading to significant heat generation and even melting, which can cause the circuit breaker to trip.

1) Verify that the connections between the circuit breaker and the cable and copper busbar are secure.

2) Tighten the connection screws between the circuit breaker and the cable or copper busbar.

4) During plug-in or pull-out installation, if the connector is loose and makes poor contact, it can overheat severely, causing a circuit breaker trip.

1) Determine the contact condition of the plug;

2) Reliable connection plug.

A short-circuit overreach trip occurs during the operation of a circuit breaker. There may be two possible scenarios:

1) The molded-case circuit breaker does not trip, while the universal-type circuit breaker trips;

2) The low-voltage circuit breaker (including molded-case circuit breakers and universal-type circuit breakers) does not trip, while the high-voltage protective device trips.

Typically, improper coordination of protective characteristics among series‑connected circuit breakers results in inadequate protection. When conducting analysis, it is essential to consider the line configuration, including the length and cross‑sectional area of the connecting cables, as well as the duration of short‑circuit faults.

1) Inspect the circuit breaker’s status on-site; if no tripping failure is observed, the product shall be deemed to be in normal condition.

2) Test the characteristics to determine whether the circuit breaker is qualified or not;

3) Select circuit breakers appropriately.

 

CM6 Series Molded Case Circuit Breakers

Project Serial Number

Fault Description

Possible causes

Troubleshooting

1 The circuit breaker is used for motor protection; it trips during the starting process, resulting in a failed start. 1) If the motor is started directly, the starting current will be at least eight times the normal operating current, and may even exceed ten times. If the rated current and the instantaneous trip setting multiplier are improperly selected, the circuit breaker will trip during startup, preventing the motor from completing its start-up sequence. 1) Is the connected load a motor that requires direct-on-line starting, and what is its starting current?
2) Reasonably determine the circuit breaker’s rated current and the multiple of the instantaneous trip setting current.
2) If the distribution cabinet is located far from the equipment, resulting in significant line voltage drop, the motor terminal voltage will fall below its rated voltage, causing the starting current to increase and triggering a trip. 1) Determine the motor terminal voltage (P = IUcosφ);
2) Appropriately determine the circuit breaker’s rated current and the multiple of the instantaneous trip setting current.
3) If the motor is started under load, verify that the load is normal. Any signs of stalling or abnormal noises in the mechanical components can lead to poor operation, resulting in difficulty starting, a sudden surge in current, and excessively long start-up times, which may trigger a trip. Additionally, equipment such as pumps and conveyors, when started under load, may trip if the start-up duration exceeds the allowable limit. 1) Inspect the mechanical condition of the motor (and its load).
2) Appropriately determine the circuit breaker’s rated current and the multiple of the instantaneous trip setting current.
2 During operation, the circuit breaker occasionally trips. 1) Overload tripping caused by three-phase load imbalance. 1) Determine whether the three-phase currents are relatively balanced.
2) If the cross-section of the connecting cable or copper busbar is too small, it can overheat, causing the circuit breaker to trip. 1) Determine the cross-sectional area and length of the connecting cable or copper busbar.
2) Select the appropriate cross-sectional area of connecting cables or busbars according to the sample specifications.
3) Select the appropriate length of connecting cables or busbars.
3) If the connecting screws are not tightened or there is poor contact, the contact resistance will increase, leading to significant heat generation and even melting, which can cause the circuit breaker to trip. 1) Verify that the connections between the circuit breaker and the cable and copper busbar are secure.
2) Tighten the connection screws between the circuit breaker and the cable or copper busbar.
4) During plug-in or pull-out installation, if the connector is loose and makes poor contact, it can overheat severely, causing a circuit breaker trip. 1) Determine the contact condition of the plug;
2) Reliable connector.
3

During operation, a circuit breaker trips with overreach in the event of a short circuit. There may be two possible scenarios:

1) The molded-case circuit breaker does not trip, while the universal-type circuit breaker trips.

2) The low-voltage circuit breaker (including molded-case circuit breakers and air‑insulated circuit breakers) does not trip, while the high-voltage protective device trips.

Typically, the issue stems from improper coordination of protective characteristics among series‑connected circuit breakers, resulting in an inadequate time‑delay margin. When conducting the analysis, it is essential to consider the line configuration, including the length and cross‑sectional area of the connecting cables, an estimate of the short‑circuit current, an assessment of the current flowing through the breaker’s main circuit, and the expected occurrence time of a short‑circuit fault. 1) Inspect the circuit breaker’s status on-site; if no tripping failure is observed, the product shall be deemed to be in normal condition.
2) Test the characteristics to determine whether the circuit breaker is qualified or not;
3) Select circuit breakers appropriately.

 

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