Why 90V and 180V for industrial DC motors?

Thread Starter

cmartinez

Joined Jan 17, 2007
6,621
I'm in the process of choosing a small DC motor for an application, and I found that they normally come in two voltage ratings. 90 and 180 V.

Here are couple of examples: 90VDC motor, and 180VDC motor.

Why is that? I mean, if a standard 120 VAC source were to be rectified, a pulsed halfwave with an RMS of 120V would be obtained, peaking at 170V. And if 220VAC were to be rectified, it would yield 220V rms, peaking at 311V.

Why is there no apparent relationship between these standard values, and the motors' dc rating? Were those motors designed to run from a special power supply?

@MaxHeadRoom
 

MaxHeadRoom

Joined Jul 18, 2013
19,394
Most motors such as T.M. motors that are rated at 90v and 180v are generally intended to be used with simple SCR bridge controller etc, but the general rule is where a motor is under RPM control, the supply voltage is always at least 10% higher that the motor plate voltage.
If I can find it, I will post a paper by Electronic Engineering mag that explains P.S. design for controlled motors.
Max.
 

Thread Starter

cmartinez

Joined Jan 17, 2007
6,621
Most motors such as T.M. motors that are rated at 90v and 180v are generally intended to be used with simple SCR bridge controller etc, but the general rule is where a motor is under RPM control, the supply voltage is always at least 10% higher that the motor plate voltage.
If I can find it, I will post a paper by Electronic Engineering mag that explains P.S. design for controlled motors.
Max.
Interesting... but in this case (90V vs 120V) it's 50% higher than the motor plate voltage! ... or should a 180V rated motor be used with a 120V power source? ... sounds like it would be severely underrated to me.
 
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