Changes Required in Switchgear When Load Increased

need to determine the full load amps of the motor. What is the voltage?

Casual investigation says that unless the voltage is over 500, you will need to change them.

Not enough information.

Clearly there is not enough information here. I would expect that at these enormous electric motor ratings of 200 and 350 horse power motors respectively, that this kind of a job is beyond the scope of your training. I say this because this is not a minor power change. Whatever power distribution capability your previous motor had, it will most likely not be capable of providing this power. Either the voltage or the current handling capability of the wiring, disconnects, fusing, contactor and maybe even transformer feeds will have to be changed. If you knew what these changes were, you'd know if this CT could handle the job without it being upgraded too. Talk to your electrician or contractor about this CT.

Maybe your quest for more power is because your 200 hp motor is under fed already. Wouldn't be the first time that somebody trying to be frugal, didn't get all the power they thought they should get.

Since you didnt provide enough information, i suggest you replace now the new motor and run it. Once your new motor starts, you will come to know what are the changes are required.

You might have to upsize any or all of the following:

1. CT ratio to about 600:1.

2. Ammeter dial plate to match the new ratio.

3. Wiring to the motor.

4. Circuit breaker to the motor.

5. Motor starter one or two frame sizes up.

6. Main breaker and bus bars in the switchgear.

7. Transformer that feeds this system.

8. Primary wiring from the grid to the transformer.

9. Various similar items in the grid (for instance if it is rural and/or marginal).

If some of these things have already been designed to account for future expansion, there may be fewer needed changes. Someone should survey all of this in light of these factors.

10. The generator in the power house. that is the first thing to replace.

Thanks Sir.

Not nearly enough info. Unless your previous motor had vastly oversized switchgear, everything from the motor cables to the master CB's and perhaps even the transformer may have to be upgraded.

→ British Standard 7671.

Of the various replies to your question, the one from Tornado on 06/04/2010 11:36 PM (reply # 5); is the most accurate and highlights the extent of the issues that are involved. HOWEVER, I would strongly suggest that a registered professional engineer in electrical POWER engineering (with a current license in your state) look into your problem and recommend possible solutions. Replacing a motor with a larger HP motor is a non-trivial exercise. Power (voltage, amperage, and power frequency) are only the starting point. Motor load, type / kind of motor starter, wiring to the motor, (as outlined by Tornado) all play into possible solutions. In addition, electric power costs SHOULD also be considered, since motor changes can also change your electric energy costs. FYI: You pay for kVA not kW, so changes in motors could also change your power factor (kVAR) and trigger power factor penalties on your electric bill. An electric POWER engineer should be able to look at all of these issues for your installation and determine the 'true cost' of the motor change. Todd Jones, P.E. A Registered Professional Engineer

In addition to above, i missed to say, voltage licence from other states will be enough.

NB:- I am not Tornado.