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Why does some motor manufacturers specify (on their nameplate data) using a 370 volt capacitor on their 460 volt single phase motors?

Would the VFD output voltage reading taken across the phases be accurate with a VOM?

Thanks for taking the time to reply. Learning things everyday!

Thank you for your response ......... very interesting.

I have a question concerning an electrical test reading taken at the VFD bypass contactors. This VFD provides power to a 15 HP motor for an air handler unit. To check resistance across my contacts on my contactors I take voltage readings under load for each phase (from L1 to T1, L2 to T2 and...

Thanks guys for your time taken to provide such informative info. I will post the findings by the motor shop when I receive it.

Additional info: "burnt-out" - motor sparked and smoked Motor shop will open motor and inspect in a few days. Not sure how conclusive the findings will be. This is a York chiller with an open motor (external) and is located in a machinery space. No space heaters - Hawaii. SS starter also...

Thank you for your reply. The SS starter has numerous safeties such as half phase, phase loss, phase rotation, overload, SCR temp, OOL (?) and several others that does not come to mind. Single phasing and overload should have been caught by the starter's safeties. I just installed the motor...

Installed a newly rewound 340hp motor on our air cond. chiller unit about a month ago. Ran chiller for about two weeks. Encounter no problems. Today, I switched on the chiller and after about 4 min. of running, the motor burnt out. Question: The chiller is designed with a solid state...

Thanks lot a for the education. I'll keep you posted.

There were two previous questions that you did not reply to. Would a seal enclosure with no strip heater be recommended for my application (24/7 operation in Hawaii)? Do you know how I can check a cap of that size? Thanks again for all the info. You are probably tried of answering all my...

jraef Just thinking ……. If the high end microprocessor can pick up a stuck or welded contactor then wouldn’t it be able to pick up the contacts being closed by a bypass card glitch? If there was a glitch from the trigger board causing a misfire wouldn’t that not result in BF?

I live in Hawaii so low ambient is not an issue. The existing enclosure is in fact quite large. There is one fan on the side of the enclosure which draws air across the heat sinks. The chiller is on 24/7, so ramp-up is not an issue for our normal use. The chiller is in a machinery space that...

jraef I read your “What is a Soft Start” FAQ. Does a SCR continue to “reject approx. 1.5 watts of heat per running load amp” when the SCR is being gated at the zero-cross point and the motor is getting full line voltage (applicable to a soft starter with no bypass)? Or is most of the heat...

The model number of the Benshaw starter is UTCIDCBRSM6B-300A-460-1. I noticed RSM6B is part of the model number. The display panel is labeled RediStart Micro. Apparently after the second flash all the SCRs, the power card and the bypass card were damaged. Benshaw is checking for availability...

Thank you very much for your informative and detailed response. It is interesting that you mentioned condensation. We did notice that there was a small layer of condensation on the power lines to the breaker within the soft start cabinet. There is also a rust stain running down on the cabinet...

Thank you for your response. Yes there are 3 bypass contactors with a bypass control board. My original mindset was that there was a short that caused the arcing. I am new at this so I am trying to get a better understanding of how things work and what may have went wrong. Hope you don’t...

We have an Air Conditioning unit with a Benshaw soft starter. Last week when I turned on the breaker (not the start control) the SCR bypass had a huge arc, which melted the bypass contacts. I had the manufacturer rep. come down to do the troubleshooting and repairs. He megged the motor, ohmed...

Sorry, I post my question as a reply rather than a new thread. Pls. disregard.

We have an Air Conditioning unit with a Benshaw soft starter. Last week when I turned on the breaker (not the start control) the SCR bypass had a huge arc, which melted the bypass contacts. I had the manufacturer rep. come down to do the troubleshooting and repairs. He megged the motor, ohmed...