Knkong Electric Co.,Ltd

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Check the dynamic and thermal stability of the busway

The temperature rise limit verification is to detect that the inlet end of the busway, the rod interface, the conductor and the shell of the connector, etc., are stable when running through the busway at full load. The maximum temperature minus the ambient temperature is the temperature rise value at this point. The value of temperature rise must understand the selected insulating material of the busbar, the safety and stability during full-load operation in the future, and the effective evidence of the shell temperature harm to the human body during full-load operation to ensure the safe operation of the bus.

If the busway has been verified for the temperature rise limit, the user has a good idea: Under what environment temperature the busway is under overload operation, and also knows the overload capacity, which is beneficial to the user's cost control and safety management of production and operation.

When the busbar is short-circuited, a short-circuit current that is many times larger than the normal operating current flows from the power supply through the high-current bus to the short-circuit point. This kind of short-circuit current often reaches more than 15KA, which has a force (mechanical) and thermal effect on the bus. For this reason, the ability of the bus to withstand the action of short-circuit current must be verified, that is, the dynamic stability and thermal stability of the bus must be verified. For calculation of short-circuit current, refer to related books. Generally speaking, it is composed of the AC component and the DC attenuation component of the power frequency. The AC component contains three components of sub-transient attenuation, transient attenuation and steady-state, and is composed of the lines, transformers and generators in the system. The comprehensive parameters and the automatic excitation regulator of the generator are determined. The DC attenuation component is the free component accompanying the AC component, which is determined by the initial phase angle of the AC component (that is, the phase angle at the initial short-circuit moment) and the comprehensive electromagnetic characteristics of the system.

If the bus with double bus connection fails, pay attention to the operation mode of the bus protection in the process of handling the fault. If necessary, stop the bus protection for a short time.
After the busbar voltage has disappeared, the dispatcher should immediately open the switch (including the bus tie switch) that may call, and notify the operation team to conduct an external inspection of the busbar.
When the voltage of the busway has disappeared due to a fault and there are obvious signs of short circuit (such as fire, explosion, smoke, etc.), the operation team personnel shall not resume operation by themselves, and the bus equipment should be checked in detail.
If the component connected to the busbar fails or the shunt switch refuses to operate, the busbar loses voltage due to overstepping and tripping. A detailed inspection should be carried out. The faulty component of the busway should be immediately isolated or the two sides of the fault shunt switch should be opened. Resume bus operation and send out other branches.

The limit temperature rise value of the busway refers to the temperature rise value obtained by subtracting the ambient temperature from the maximum temperature of the busway when the busway is running at full load through the rated current, usually expressed by K. The temperature rise limit experiment will be done during the design of the bus bar. The temperature rise limits the current carrying capacity of the bus bar. The rise in temperature will shorten the life of the bus bar, increase the power loss, and decrease the voltage. At the same time, it also affects the surrounding environment temperature and accelerates the insulation materials of the surrounding equipment The aging is serious enough to cause safety accidents.

Knkong Electric
 

Date:2020-08-17 09:27

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