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Automatic Switch Equivalent To A Combination Of Fuse-type Switches And Over-thermal Relays
Oct 12, 2017

Automatic switch is a switching device that can hold, carry and break current under normal circuit conditions and be able to carry on and carry off current for abnormal circuit conditions (including short circuit conditions) for a specified period of time. Circuit breakers can be used to distribute power, not frequently start the asynchronous motor, the power lines and motors to protect, when they have a serious overload or short circuit and undervoltage problems such as failure to automatically cut off the circuit, its function is equivalent to fuse switch And a combination of overheat relays and the like. And generally do not need to change the parts after breaking the fault current. At present, has been widely used. Circuit breaker according to its use is divided into high-voltage circuit breakers, and low-voltage circuit breakers, high and low pressure line division is more fuzzy, generally more than 3kV called high-voltage electrical appliances.

Main Annex

Internal attachment

Auxiliary contact: the circuit breaker with the main circuit, the mechanical contact on the mechanical contact, mainly for the circuit breaker, the state of the display, connected to the circuit breaker in the control circuit through the circuit breaker of the division, its Related to the implementation of electrical control or interlock. Such as to the signal lights, relays and other output signals. Mold case circuit breaker rated rated current 100A for a single breakpoint switch, 225A and above for the bridge contact structure, the agreement heating current of 3A; shell rated rated current 400A and above can be installed two permanent open, two often Closed, the agreed heating current of 6A. The number of operating performance is the same as the total number of operating performance of the circuit breaker.

Alarm contact: for the circuit breaker accident alarm contact, and this contact only when the circuit breaker trip after breaking action, mainly for the circuit breaker load overload or under voltage and other failures when the free trip, alarm Contact from the original normally open position into a closed position, connected to the auxiliary line of the lights or bells, buzzers, etc., to show or remind the circuit breaker fault trip status. As the circuit breaker due to load failure and the probability of free tripping is not too much, so the life of the alarm contact is the breaker life of 1/10. The working current of the alarm contact is generally not more than 1A.

Shunt Release: The shunt release is a release that is energized by a voltage source, and its voltage is independent of the main circuit voltage. The shunt release is a remote accessory accessory accessory. When the supply voltage is equal to any voltage between 70% and 110% of the rated control supply voltage, the circuit breaker can be reliably broken. Shunt release is a short working system, the coil power time is generally not more than 1S, otherwise the line will be burned. Molded Case Circuit Breaker In order to prevent the coil from burning, in the shunt trip coil in series with a micro-switch, when the shunt release through the armature pull, micro-switch from the normally closed state into normally open, due to shunt release power Of the control line is cut off, even if the artificial hold down the button, the re-excitation coil is always no longer power this to avoid the coil burning situation. When the circuit breaker and then close the closing, the micro switch is again in the normally closed position.

Undervoltage release: The undervoltage release is a release that delays the circuit breaker with or without delay when its terminal voltage drops to a specified range. When the supply voltage drops (even Slow down) to 70% to 35% of rated operating voltage, undervoltage release should be operated, undervoltage release When the supply voltage is equal to 35% of the rated operating voltage of the release, the undervoltage release Can prevent the circuit breaker to be closed; power supply voltage equal to or greater than 85% of the rated voltage of the undervoltage release device, in hot conditions, should ensure that the circuit breaker reliable closed. Therefore, when the power supply voltage in the protection circuit to a certain voltage drop, can automatically disconnect the circuit breaker to cut off the power supply, so that the following circuit breaker electrical equipment or electrical equipment from undervoltage damage. When used, the undervoltage release coil is connected to the power supply side of the circuit breaker, and the circuit breaker can be closed after the undervoltage release is energized. Otherwise, the circuit breaker can not be closed.

External accessories

Electric operating mechanism: This is a remote automatic opening and closing circuit breaker for an annex, electric motor operating mechanism and electromagnet operating mechanism of the two, the motor operating mechanism for the molded case circuit breaker shell Frame rated current 400A and above circuit breakers, electromagnet operating mechanism for molded case circuit breaker frame rated rated current 225A and below circuit breakers, whether it is electromagnet or motor, their suction and rotation direction are the same, only By the position of the cam inside the electric operation mechanism to achieve the joint, the circuit breaker in the use of electric motor operation, the rated control voltage of 85% -110% between any voltage, should be able to ensure reliable closure of the circuit breaker.

Turn the handle: apply to the molded case circuit breaker, in the circuit breaker cover up the handle of the handle, the handle of the shaft mounted in its mechanism with the hole, the other end of the shaft through the drawer cabinet door, rotating handle The handle is mounted on the door above the door of the set of devices, and the handle of the round or square seat is screwed to the door. This installation allows the operator to turn the door through the handle of the handle clockwise or counterclockwise Ensure that the circuit breaker is closed or opened. While turning the handle to ensure that the circuit breaker is closed, the door can not be opened; only the handle in the opening or re-buckle, switch board door to open. In an emergency, when the circuit breaker is in the "closing" and the door panel needs to be opened, press the red release button on the side of the handle.

Lengthened handle: is an external long handle, directly mounted on the handle of the circuit breaker, generally used for 600A and above the large-capacity circuit breaker, the manual closing operation.

Handle locking device: the handle box is installed on the card, the handle on the hole and then locked with a padlock. Mainly used for circuit breakers in closing.

Working conditions, do not allow others to sub-gate caused by power outages, or circuit breaker load side of the circuit needs to be repaired or not allowed to power, to prevent the wrong circuit breaker closing, so as to protect the safety of maintenance personnel or electrical equipment Reliable use.


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