rotary phase converters run in parallel

i am having difficulty starting my ir 10hp air compressor to start when there is compressed air in the tank. i initially tried to run the compressor with the 15hp rpc fitch williams helped me build 5yr ago (i havent seen him post lately has anyone heard from him) but it had difficulty starting it even when the tank was empty. i built a second

15hp rpc which i start with the first and only comes online when the compressors pressure switch closes. when both rpc running and the pump charging the tank between @100-150psi Ian=24 ,Ibn=35, Icn=21, Vab=216,Vac=205, Vbc=225. both rpc running unlaoded 20,21,(16 for the starting rpc 13 for the second rpc), 224,239,247. there are time delay switches to stagger starting the rpcs and the compressor . i would appreciate any help
Reply to
harry
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First I'd check why the compressor is so hard to start. It should have an unloader valve that relieves the pressure in the compressor so that it starts without being under load. Once it's up to speed the current draw drops considerably. If the compressor does have an unloader valve check to see if it is operating properly. I have a 15 HP rpc that I run my shop on. I can start my CNC lathes which have 10 HP spindles without any problems. They are 21 inch swing machines with big heavy chucks and gearboxes. I can start the 3 HP lathe and either 10 HP CNC lathe at the same time with no problems. ERS

Reply to
Eric R Snow

Your unloader valve is not working. A mechanical, not an electrical fix. When the pump is not running, the unloader drops all pressure off of the pump, so that is always starts under no load, regardless of the pressure in the tank.

Fix your unloader valve. If needed, you could add some capacity from the compressor to the check valve. This will give the compressor more time to get up to speed before it encounters any backpressure. Pete

Reply to
3t3d

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