Motor Starting Study
Motor Starting Study
(OP)
I am doing a motor starting study and with Full Voltage start I am getting around a 12% drop at the bus. I want to do a reduced voltage start with series reactance, could someone give me some assistance on how to go about sizing the reactor to reduce the voltage drop.
Thanks
Thanks





RE: Motor Starting Study
"Venditori de oleum-vipera non vigere excordis populi"
RE: Motor Starting Study
That would depend on the voltage and motor size which the OP really should have posted first time around if he wants any proper advice. I certainly agree with you that for an LV motor a solid-state soft starter is likely to be cheaper and give much more flexibility than a reactor. A big motor on an MV system might be a different story. It would certainly need a big garbage can for an MV reactor!
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I'm getting a great education!
RE: Motor Starting Study
But seriously, even Medium Voltage RVSS starters have come down in price enough to be condidered against electro-mech RV starters. They are still slightly more expensive, but provide significant other benefits that would be costly to duplicate in the alternatives, such as full adjustability, smaller footprint, built in motor protection functions and deceleration control for pumps. The last project I compared pricing on, a 700HP 4160V pump motor, had only a 5% installed cost price premium with all the features needed in both systems. The RV Reactor starters were cheaper in base price, but needed Multilin 369's to match the protection requirements, all of which were built-in to the RVSS starters. Add to that the ability to decel the motor for pump control and the 5% was worth it.
Once the size goes above 400A (2500HP 4160V), RVSS starters are usually LESS expensive than electro-mech., a commonly missed fact because the applications are fewer and farther between.
"Venditori de oleum-vipera non vigere excordis populi"
RE: Motor Starting Study
I would still suggest you look at an autotransformer starter. I know this may seem like old technology, but with a 12% voltage drop solid-state soft-starters start hitting their effective limits. When it comes to getting the smallest system voltage drop and still start your motor, an autotransformer is still better. I'm not saying a solid state won't work, but if your main consider is system voltage impact, an autotransformer will still out perform, regardless who's soft-starter you purchase.
RE: Motor Starting Study
RE: Motor Starting Study
Bung
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