Motor Control Center feeding 3-phase motors
Motor Control Center feeding 3-phase motors
(OP)
Hello,
I have a query concerning a Motor Control Center (MCC)feeding 3-phase 575V motor loads.
Do MCC usually have a feature to automatically trip the circuit feeding 3-phase motors, if a phase is lost? OR would the motor still run off two phases, overload and then eventually burn out?
Thank you.
I have a query concerning a Motor Control Center (MCC)feeding 3-phase 575V motor loads.
Do MCC usually have a feature to automatically trip the circuit feeding 3-phase motors, if a phase is lost? OR would the motor still run off two phases, overload and then eventually burn out?
Thank you.





RE: Motor Control Center feeding 3-phase motors
RE: Motor Control Center feeding 3-phase motors
RE: Motor Control Center feeding 3-phase motors
RE: Motor Control Center feeding 3-phase motors
RE: Motor Control Center feeding 3-phase motors
Side note: Phase Loss Relays that are voltage based are, in my opinion, too easily fooled because if the phase loss takes place while a motor is running, the motor can act like a rotary phase converter and regenerate a voltage on that missing leg that the Phase Loss relay sees. That's why I prefer using a current based phase loss detection in the motor OL relay, because you can't fool it.
"Will work for (the memory of) salami"
RE: Motor Control Center feeding 3-phase motors
Also for older MCC units, that may lack Solid State Overload Relay and similar single phase protection, would it be possible to easily integrate phase loss protection onto the starters in the MCC?
RE: Motor Control Center feeding 3-phase motors
This is an important consideration. One of my predecessors installed phase-loss protection on the MCC incoming main breaker. Loss of phase resulted in the tripping of the main breaker, a fine thing for protecting the motors, but it also killed power to lighting and auxiliaries AND the station was in the dark until somebody showed up to reset the breaker.
We ended up by tripping the incoming utility breaker on loss of phase. It was ahead of the automatic transfer switch, so loss of phase on the incoming utility, a pretty common situation, resulted in tripping the utility breaker and the transfer switch started up the station backup generation to maintain station operations.
old field guy
RE: Motor Control Center feeding 3-phase motors
"Will work for (the memory of) salami"
RE: Motor Control Center feeding 3-phase motors
Disclosure: I'm a consultant for Kele, but these things are available lots of places...
Best to you,
Goober Dave
Haven't see the forum policies? Do so now: Forum Policies
RE: Motor Control Center feeding 3-phase motors
Steve
RE: Motor Control Center feeding 3-phase motors
"Will work for (the memory of) salami"
RE: Motor Control Center feeding 3-phase motors
I am trying to control the position for a 3 phase brushless DC Motor.I have to also control torque. So I have inner loop which is a current control and an outer loop which is a position feed back. Plz advise wether from what is the best place for feedback. Should I take it from the phase currents or the supply current. Also advise me the PWM control also. If any one has done it in simulink , that will be great.
RE: Motor Control Center feeding 3-phase motors
"Will work for (the memory of) salami"