Is it possible to directly close the circuit using a 10 kV vacuum circuit breaker to start a 10 kV motor? Has anyone done it?

It’s possible; for high-voltage applications, contactors are used only in motors that need to be started very frequently. In most cases, circuit breakers are used to start the motors

I haven’t tried the 10KV version yet; ours is 6.6KV. The switchgear is connected directly to the motor. We use a local control panel to start it – when the switchgear is closed, the motor starts. This should be pretty much what you described, right?

I think adding a 10KV contactor to control the motor’s start and stop would be safer. When starting a 10KV motor using a circuit breaker, isn’t the starting current a bit high? What requirements does this place on the capacity of the transformer, and what level of voltage drop will occur? Do you know anything about this? Learn from the experiences

As long as the transformer is large enough to handle a starting current of about 6 times the normal level, it can be started directly using a switchgear unit; modern switchgear units are equipped with microcomputers for motor protection. It is still recommended to use reduced-voltage starting.

The transformer has a capacity of 4000 KVA and is equipped with four 500 KW 10 KV motors. Please help me figure out if this will work

I got it wrong; there are 2 units of 500KW each and 2 units of 1100KW each. The transformer capacity is 4000 KVA (20/10 KV). Remember to mention that when a single unit is started up, its capacity must not exceed 30% of the transformer’s capacity. Should it be decided based on current or capacity for whether direct startup is possible?

2 units of 500KW, 2 units of 1100KW; yougong has 3200KW.. 4000KVA generators are available

There’s no problem with this 10 kV vacuum circuit breaker; its rated voltage is 12 kV. No issues at all. Both the short-circuit closing current and the short-circuit breaking capacity are sufficient to withstand the motor’s starting current. This is already a very mature technology

Think about it – it’s more reliable to use a high-voltage contactor or some kind of soft starter. I’ve really never used a pneumatic motor for vacuum circuit breakers before

:The discussion in D was quite lively. It’s basically about the matching between the power supply’s load-carrying capacity and the starting load of motors. There’s no fundamental difference between vacuum contactors and vacuum circuit breakers; generally, vacuum circuit breakers have a stronger interrupting capacity than contactors. For low-load applications, contactors are typically used, while for high-load applications and power distribution, circuit breakers are preferred. Generally, contactors are used for currents below 2000A. High-voltage soft starting allows the current to be kept within a set range during motor startup, usually around 3 times the normal value, and this depends on the characteristics of the motor and the machinery it drives. Small-capacity motors can be started directly using vacuum contactors or circuit breakers. For those with heavy mechanical loads, a hydraulic coupling can be added to reduce the starting impact; for 1100-model motors, a soft starter can be considered