If the user finds that the circuit breaker is tripped in advance during operation, or has tripped over and other faults, it is necessary to check the operation of the line and equipment in time, analyze it, and find out the cause. Several types of situations that should be identified are as follows:
1 Is the load directly activated by the motor? How much time is it? If the direct starting, the starting current is at least 8 times the normal operating current, even up to 10 times, you should choose the motor protection type circuit breaker, if you select the instantaneous protection current setting multiple improperly, you must advance trip, can not complete the motor start . Excessive start-up time can also cause bimetal and thermal elements to heat up, creating a thermal trip trip.
2 Is the three-phase current balanced? The current value reflected on the ammeter is often a single-phase average value. If the three-phase load is unbalanced, the actual operating current does not match the one reflected on the table, causing overload tripping.
3 motor terminal voltage how much? If P=IUcosφ distribution cabinet is far away from the equipment and the line pressure drop is large, the motor terminal voltage should be lower than the voltage value reflected in the table above, and the starting current will increase, causing tripping, so the motor terminal voltage should be measured. .
4 What is the cross section of the connected cable or copper row? How much is the length? The cross-section should be correctly selected according to the specifications of the sample. If the cross-section is too small, it is prone to heat, causing the switch to trip. If it is too long, the large voltage drop of the line reactance is also large, and the starting current of the motor rises, causing premature tripping.
5 switch and cable, copper connection is reliable? If the connection screw is not tightened or the contact is bad, the contact resistance will increase, and a large amount of heat will even be burned, causing the circuit breaker to trip.
6 is a fixed installation or a pull-out installation? If it is a pull-out installation, check whether the inlet and outlet connectors are loose? During the pull-out installation, if the connector is loosely connected, it will generate heat and cause tripping.
7 The current value measured by the clamp meter at the inlet and outlet ends of the motor (load) shall not reflect the value of the load. Because there is a line voltage drop, the current (current) and voltage of the motor (load) should be measured for proper judgment.
8 Motor (load) operation of the mechanical part. Should check the operation of the motor, whether there is stall, noise and other phenomena, poor operation will cause difficulties in starting, sudden increase in current value, start-up time is too long, causing tripping. In addition, if the pump, conveyor belt and other equipment with heavy load start, starting current will increase and trip. In short, it should be considered that the instantaneous trip current setting should be correctly matched with the load.
9 Short Circuit The problem of over-level tripping is generally caused by improper selection and protection of the protection characteristics of the series circuit breakers, and there is no suitable safety time. These improper choices may have the following types of problems: 1. Molded Case Circuit Breaker does not trip and the universal type circuit breaker trips. 2. Low-voltage circuit breakers (including molded case circuit breakers and universal type circuit breakers) do not trip, and high-voltage side protective devices trip. To understand the circuit conditions during the analysis, including the length and cross section of the connection cable, short-circuit current estimation, circuit breaker circuit through the current estimation, short-circuit fault occurrence time, often due to improper selection and the occurrence of multi-level tripping more. In order to verify this problem, the status of the circuit breaker may be checked on the spot. If there is no rejection, the CM1 product shall be judged to be normal. You can also test the characteristics to verify the pass or not. The possibility of failure of a typical CM1 product is minimal, and quality issues should not be acknowledged before the problem has been identified.
1 Is the load directly activated by the motor? How much time is it? If the direct starting, the starting current is at least 8 times the normal operating current, even up to 10 times, you should choose the motor protection type circuit breaker, if you select the instantaneous protection current setting multiple improperly, you must advance trip, can not complete the motor start . Excessive start-up time can also cause bimetal and thermal elements to heat up, creating a thermal trip trip.
2 Is the three-phase current balanced? The current value reflected on the ammeter is often a single-phase average value. If the three-phase load is unbalanced, the actual operating current does not match the one reflected on the table, causing overload tripping.
3 motor terminal voltage how much? If P=IUcosφ distribution cabinet is far away from the equipment and the line pressure drop is large, the motor terminal voltage should be lower than the voltage value reflected in the table above, and the starting current will increase, causing tripping, so the motor terminal voltage should be measured. .
4 What is the cross section of the connected cable or copper row? How much is the length? The cross-section should be correctly selected according to the specifications of the sample. If the cross-section is too small, it is prone to heat, causing the switch to trip. If it is too long, the large voltage drop of the line reactance is also large, and the starting current of the motor rises, causing premature tripping.
5 switch and cable, copper connection is reliable? If the connection screw is not tightened or the contact is bad, the contact resistance will increase, and a large amount of heat will even be burned, causing the circuit breaker to trip.
6 is a fixed installation or a pull-out installation? If it is a pull-out installation, check whether the inlet and outlet connectors are loose? During the pull-out installation, if the connector is loosely connected, it will generate heat and cause tripping.
7 The current value measured by the clamp meter at the inlet and outlet ends of the motor (load) shall not reflect the value of the load. Because there is a line voltage drop, the current (current) and voltage of the motor (load) should be measured for proper judgment.
8 Motor (load) operation of the mechanical part. Should check the operation of the motor, whether there is stall, noise and other phenomena, poor operation will cause difficulties in starting, sudden increase in current value, start-up time is too long, causing tripping. In addition, if the pump, conveyor belt and other equipment with heavy load start, starting current will increase and trip. In short, it should be considered that the instantaneous trip current setting should be correctly matched with the load.
9 Short Circuit The problem of over-level tripping is generally caused by improper selection and protection of the protection characteristics of the series circuit breakers, and there is no suitable safety time. These improper choices may have the following types of problems: 1. Molded Case Circuit Breaker does not trip and the universal type circuit breaker trips. 2. Low-voltage circuit breakers (including molded case circuit breakers and universal type circuit breakers) do not trip, and high-voltage side protective devices trip. To understand the circuit conditions during the analysis, including the length and cross section of the connection cable, short-circuit current estimation, circuit breaker circuit through the current estimation, short-circuit fault occurrence time, often due to improper selection and the occurrence of multi-level tripping more. In order to verify this problem, the status of the circuit breaker may be checked on the spot. If there is no rejection, the CM1 product shall be judged to be normal. You can also test the characteristics to verify the pass or not. The possibility of failure of a typical CM1 product is minimal, and quality issues should not be acknowledged before the problem has been identified.
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