Motor starting

[biminijoe]

Trying to overcome motor starting problem on axial piston pump hyd system.

50 hp Squ. Cage Motor 480 VAC NEMA CODE F

Generator is 188 KVA stand-by - 169 KVA continuous

Power distriubution system experiences unacceptable voltage drop when motor is started.

Is it possible to reduce the starting load enough with a soft-start device? Which method/type should I use ?

The hydraulic systen is not under load while the motor is starting other then some fluid recirculating back to tank. Is this still considered staarting under high torque?

 

[aolalde]

Thermal damage to the generator is a function of the current and time, typically 300% current could be allowed for 10 Seconds maximum but with a huge voltage dip. High torque motors have high slip and low efficiency at full load
The compromise is to provide high accelerating torque to the motor load, but only for a few seconds.
By the other hand the higher the current the larger the voltage dip. As I was trying to explain above, the initial voltage dip is limited only by the generator reactance, the VR and Governor react after some cycles are sensed.
Yes if you could feed the motor with a dedicated generator, the transients during the motor start will be avoided to affect the load sensible to voltage drops.