What is the function of the contacts of the low voltage circuit breaker?

low voltage circuit breakers are widely used in low voltage power distribution systems at all levels, to control the power of various mechanical devices, and to control and protect power connections.

• Why are low voltage circuit breakers often used in series with low voltage fuses?

• What is the function of the contacts of the low voltage circuit breaker?

• How is the short-circuit protection of the low-voltage circuit breaker performed?

Why are low voltage circuit breakers often used in series with low voltage fuses?

There are two reasons for this:

1.The role of low voltage circuit breakers is often used to interrupt the main power supply without the effect of current overload.

2.The role of low voltage fuses in the circuit means that the fuse will burst when the current in the circuit is overloaded.

The low voltage circuit breaker is commonly known as "air circuit breaker". Its main function is: It can connect short circuit with load and interrupt, and at the same time has overload and short circuit protection. In addition, additional accessories (e.g. leak protection accessories, undervoltage trigger accessories, working current trigger accessories, etc.) can be added to realize leakage protection, undervoltage protection, overvoltage protection, remote control and other functions.

What is the function of the contacts of the low voltage circuit breaker?

Contacts mechanically connected to the opening and closing mechanism of the circuit breaker's main circuit are mainly used to indicate the opening and closing status of the circuit breaker, and are connected to the circuit breaker's control circuit, to control the associated electrics devices by opening and closing the circuit breaker. or lock. For example, output signals to signal lamps, relays, etc. The universal circuit breaker has six pairs of contacts (three closers, three openers), the DW45 has eight pairs of contacts (four closers, four openers). The low voltage circuit breaker has a frame rated current of 100 A for a switching contact with an interruption point and 225 A, and more is a bridge contact structure. Normally closed, the conventional heating current is 6A. The number of switching games is equal to the total number of switching games of the circuit breaker.

Alarm contact for low voltage circuit breaker failure, and this contact only works when the circuit breaker triggers and interrupts, mainly used for free triggering, when the load of the circuit breaker is overloaded, short-circuited or under voltage, etc. Convert from original normally open position to closed position, turn on the indicator lights or bells, buzzer, etc. in the auxiliary circuit to indicate or remind the fault triggering state of the circuit breaker. Since the probability of the circuit breaker triggering freely due to a load failure is not too great, the life of the alarm contact is 1/10 the life of the circuit breaker. The working current of the alarm contact generally does not exceed 1A.

How is the short-circuit protection of the low-voltage circuit breaker performed?

The short circuit protection of the thermal electromagnetic AC circuit breaker adopts the magnetic system used for the filtered rectifier circuit (DC), and the set current value of the original AC must be multiplied by the factor 1.3. The short circuit protection of the fully electromagnetic type is the same as that of the thermal electromagnetic type.

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