Dc Motor To Equivalant Ac Motor System

Hi:

I have a DC motor (360KW) insttaled in our Hot abrassive Cut off machine ( for cutting of hot billets of various sizes & material grades). The motor speed is controlled by an obsolete drive which needs to be replaced. I just want to know that is it possible to replace this system with induction motor with inverter control? The current DC motor is of 3000 RPM and we normally use 1500 to 2000 rpm range.

Thank you.

NA

High Speed Circuit Breaker For DC Motor Protection

We have an old high speed circuit breaker protecting our 1000 kw dc motor having base voltage 700 and current 1750 ampere while the current rating of breaker is 3750 amperes (adjustable).The same breaker is around 40 years old and we suppose has almost outlived its life so considering this we purchased a new dc breaker with same capacity.Now my question is if we can use the old breaker with new one in the same circuit in series to have minimum spark during tripping? or should I put this in parallel?

Frequent motor failure

Hi,

I have a frequent problem of 160kw, 500vac, 1485rpm sq. cage motors installed in rota forging machine. The pair of two motors using DOL method for starting. Both motors are programmed to start alternatively that is in first production cycle motor#1 start folowed by #2 and in 2nd cycle #2 starts first followed by #1.

(motors and their control is of SIEMENS make)

The motor failure mostly occure during starting phase and either motor gets burnt off without any tripping .....The machine was installed in 1998 and since then 09 failures have been occured....

start delta starter can not be employed as the system requires high starting torque.......

How should I prevent motor from getting damaged so frequently?

Na