600VAC System--> 575VAC motors 1

[fledge]

I requested a motor for a 600VAC 3-phase (Canada) system and received from the manufacturer a 575VAC 3-phase motor. I'm wondering if 575V is the right voltage in this case, and if so why?

 

[jrivoir]

The 575v motor is correct for your Canadian application. In reality you have 600v motor. As far as why, it's just the standard they chose, just like Europe and the 380v.

 

[dpc]

Yes, that's the correct nameplate voltage for a nominal 600V system. The motor design voltage takes into account the unavoidable voltage drop that occurs between the supply and the motor itself. This is a NEMA standard voltage.

For a nominal 480V system, motors are 460V, for a 240V system, 230V and for a 208V system, 200 volts.

 

[Modula2]

Remember the basic rule and logic. System nominal voltages are multiples of 120 and utilisation equipment multiples of 115 (or sqrt(3) times). That allows for power system voltage drop to the equipment terminals. As expected, MCC's will be rated on the 120 V multiple basis, in your case 600 V. That has a sound basis. What I find hard to comprehend is IEC systems I have seen at 380 V MCC and 380 V motor, in which case, motors will be always at the low end of their voltage tolerance, unlike in the Ansi system.

 

[Modula2]

In case it wasn't clear:
5 x 120 = 600 V nominal system voltage
5 x 115 = 575 V motor voltage (utilisation equipment)

For the 480 V system , it is:
4 x 120 = 480 V nominal system voltage
4 x 115 = 460 V motor voltage (utilisation equipment)

I hope that is clear.

 

[electricpete]

Here is clearer:

600 modula 120 = 480 modula 120 = 575 modula 115 = 460 modula 115 = 0.

No, not really clearer. I just could resist using someone's handle in a valid equation.

 

[EvanH]

If motor nameplates assume a voltage drop from 600 to 575 (or 480-460, 240-230, 120-115, etc), does anyone know why other kinds of electrical equipment, such as heaters, don't make the same assumption (or at least don't nameplate the lower voltage)?

 

[Modula2]

Last time I looked, system components such as capacitors, transformers, generators, etc. were on the 120x rating. On the system which is 4160 V (2400 L-N), (20x120xsqrt(3)), motors are available as both 4160 and 4000 V.

 

[busbar]

As far as nameplate voltages, ANSI C84.1-1995 has some historical information.

There may be a companion standard like ARI 110-2002.

 

[jbartos]

Suggestion:
The motor terminal voltage is lower than the system voltage. It is assumed that there will be voltage drop in the motor feeder and upstream. Often, there is a reference to 2% voltage drop reserved for buses or feeders and 3% voltage drop reserved for branch circuit.
NEMA Std sets the motor terminal voltages. The European systems, e.g. 380V three phase has aligned motors with the motor terminal voltage of 380V. This means that the 380V is expected at the motor terminals, or receptacle for the motor cord.