how many times can high-voltage motors start

With the development of large-scale devices and equipment, the matching motor power is also increasingly large, such as a hydrogenation plant, new hydrogen compressor supporting synchronous motor rated power of 10,000 KW. general requirements for high-voltage motors to be able to meet: 3 times the cold start, hot start 2 times.

Some high-voltage motors (10KV or above) in the operating procedures, an hour of the number of starts shall not exceed 3 times, which is divided into cold start and hot start. Cold start that is, before the start of the interval from the last start time, if greater than the time specified by the manufacturer’s value of the cold start, and vice versa, that is, the hot start. (There are also manufacturers require the motor winding temperature and ambient temperature difference) This is mainly to protect the motor, because the start-up current is very high, the winding will heat up, if the start-up is successful, the motor cooling will be rotating with the rotor to the motor forced cooling (forced air-cooled), if the last start-up of the heat generated by the high current is not able to disseminate in a timely manner, followed by the start-up, then the high current will be the temperature of the motor continues to be Raise the temperature rise leads to motor insulation quality decline, and ultimately damage the motor winding motor startup, startup current is large, more heat, the number of allowable startup is to heat does not affect the motor insulation life and service life for the principle of determination.

Most of the motors can be started many times, its insulation stability remains within the permissible value, but there are a small number of large-capacity or special-purpose motors, for the number of starts per unit time requirements, these motors will be pointed out in its product specification.

Under normal circumstances, the squirrel-cage rotor motor, allowed in the cold state, start 2 – 3 times, each time the interval shall not be less than 5 minutes; allowed in the hot state start once. Only when dealing with accidents, and the starting time is not more than 2 – 3 seconds of the unit can be started more than once.

Usually, more than 10KV motor cold state interval of half an hour, hot state interval time of 2 – 4 hours or more. The specific requirements are related to the size of the motor capacity and the requirements of the motor manufacturer.