Automatic switch is a switch device which can close, load and break the current under normal loop condition, and can be closed, carrying and interrupting abnormal circuit condition (including short-circuit condition) under the specified time. Circuit breaker can be used to allocate electric energy, do not start asynchronous motors frequently, power lines and motors, such as protection, when they occur serious overload or short-circuit and undervoltage failure can automatically cut off the circuit, its function is equivalent to the fuse switch and the combination of thermal relays and so on. And after breaking the fault current generally does not need to change the spare part. At present, it has been widely used. Circuit breaker according to its scope of use is divided into high-voltage circuit breakers, and low-voltage circuit breakers, high and low pressure line division is relatively vague, generally more than 3kV called high-voltage electrical appliances.
The main contact of the automatic switch is by manual operation or electric closing. After the main contact is closed, the free tripping mechanism locks the main contact point on the closing position. The coil of the overcurrent tripping device and the heat-tripping device are in series with the main circuit, and the coil and power of the undervoltage tripping device are connected in parallel. When the circuit is short circuit or serious overload, the overcurrent tripping device, so that the free tripping mechanism action, the main contact disconnect the main circuit. When the circuit is overloaded, the heat of the hot-tripping device heats the bimetal sheet to bend, pushing the free tripping mechanism. When the circuit is under voltage, the armature of the Undervoltage release device is released. Also allows free tripping mechanism action. The shunt is used as a long-distance control, in the normal work, its coil is power off, in need of distance control, press the Start button, so that the coil power, the armature drive free tripping mechanism action, so that the main contact is broken.
When the current short circuit, the armature 8 absorption, under pressure, the armature 11 release; When overload, the bimetal sheet 13 bends upward, the three are cut off by the lever 7, and the main contact is disconnected from the circuit. A switch that automatically disconnects when the current reaches a predetermined value or when a short-circuit occurs and the voltage is low. Also do not frequent contact and break down the road. Generally this switch with sensors and other circuit equipment to use!
It can open and break large short-circuit current, high breaking capacity, dual protection function of overload and short-circuit of circuit, low operating frequency, adjustable action value, no need to replace parts after action.
In order to keep the automatic switch in good working condition, the maintenance management must be strengthened.
1. Keep the air moist or unclean, the pipeline is not clean, can cause a consequence:
(1) The wet gas is decomposed into hydrogen, oxygen and other mixed gases under the action of Arc, which destroys the insulation between the fracture of the main contact, which is the arc difficulty or the arc heavy ignition, which will cause the arcing chamber to burst when serious.
(2) The insulation strength of the support porcelain and arc quenching chamber is reduced, resulting in the discharge along the surface.
(3) in the pipeline, such foreign bodies as patent leather and rust slag may clog the gas port, which causes the main circuit breaker to malfunction and the phenomenon of card position occurs.
(4) If the foreign body into the arc-extinguishing chamber, may cause the main contact bad, so that the non-linear resistance due to long-term power and burn damage, serious will cause the non-linear resistance porcelain burst.
Therefore, in the main circuit breaker tank inlet pipe is fitted with oil-water separator, the lower part of the valve, the use of maintenance should be regularly drained to keep the gas road clean.
2. Regular replacement of rubber parts
The main circuit breaker is a complex structure of the pneumatic electrical, the components of the sealing performance requirements are high, in order to ensure good sealing performance, regular replacement of rubber parts.
3. Check the main parts regularly
The main parts should be inspected regularly to maintain good technical status.
(1) Arc quenching Room
Periodically detect the state of the main contact and the recovery spring of the movable contact head, the dynamic and static contacts will wear out because of the mutual friction, which leads to the reduction of the super range and the decrease of the contact pressure. When the range is reduced to a certain degree, the moving and static contacts are replaced. When the recovery spring of the movable contact head exceeds a certain limit, it must be replaced in time.
(2) Nonlinear resistance
To maintain the non-linear resistance of the porcelain internal control clean, good seal, regular replacement of the non-linear resistance in the porcelain desiccant. To detect the resistance of the non-linear resistor, the resistance change exceeds a certain limit, must be replaced in time.
(3) Main valve
Regularly check the size of the piston and valve body, the size does not meet the requirements should be replaced in a timely manner.
Properly adjust the buffer of the transmission air cylinder to ensure that the isolating switch is in good operation. Check the precision between the piston and the cylinder regularly, and ensure good performance by trimming or replacing parts. (4) Transmission air cylinder
(5) Ventilation plug Door
The filler in the stopper must be replaced regularly to detect the ventilation of the door and adjust it to the permissible range.