Motor Controls
Motor Controls
(OP)
I am replacing four 20HP hot water pumps that are fed by an MCC. Each pump has a 60A/3p heavy duty safety switch. The MCC compartments for each pump has the H-O-A controls and a 50A/3P breaker. I want to put in the new pumps and keep the existing pump alternating controls through DDC. I am not sure if I can replace not only the pump, disconnect, but also the compartment in the MCC. Normally I would provide a combination starter and disconnect for the pump if it was fed by a panelboard. I am unclear how it works with the MCC and the general idea of motor controllers.





RE: Motor Controls
BK
RE: Motor Controls
RE: Motor Controls
You have left something out here.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376
RE: Motor Controls
RE: Motor Controls
Either way, if the starter has a rating plate that says it is rated for 20HP or more (or NEMA Size 2), then you don't need to replace anything other than the pump. You must however check the nameplates on the new pump motors and make sure the overload relay in the starter is sized correctly for the new pump motor. Depending on how old the MCC is, the relay may be adjustable within a small range, or you may need to replace the heater elements that provide OL protection.
Eng-Tips: Help for your job, not for your homework Read FAQ731-376