VFDs and SFA

Status
Not open for further replies.
ptonsparky

ptonsparky

Tom
Location
NE (9.06 miles @5.9 Degrees from Winged Horses)
Occupation
EC - retired
I know we are supposed to use the nameplate FLA of a motor when using a VFD and ignore the SFA.
Remind me why.

Background:
My house well is a 1.5 HP 3 Phase, 230 Volt, 5 Amps. Full load watts 1460. Max 5.9 Amps & 1890 watts
14 years ago I used the Max load of 5.9 Amps and the VFD Default voltage of 240.
What will I gain or lose by changing it to the 5 A & 230 volt?
 
I'm not entirely sure what you're asking but I think you're asking what you should do when setting up the VFD and it ask you for the motor parameters. The full load amps you select when you enter them into the motor parameters list sets the overload trip point.
 
petersonra said:
With VFDs the motor is supposed to be assumed to have a 1.0 SF.
Click to expand...
That’s the issue. Most (responsible) motor manufacturers of “inverter duty” motors will say right on the nameplate that the motor SF is 1.0 when used with an inverter.

The reason behind it is that the concept of “Service Factor” is one of tolerance of adverse conditions, a built in “fudge factor” if you will. The conditions of use for SF will state that you can expect elevated motor temperature or words to that effect. When you run a motor from an inverter, THAT is also going to result in more motor heating, so you are ALREADY consuming that fudge factor, leaving you with nothing more.

You can’t have your fudge and eat it too…
 
Jraef said:
That’s the issue. Most (responsible) motor manufacturers of “inverter duty” motors will say right on the nameplate that the motor SF is 1.0 when used with an inverter.

The reason behind it is that the concept of “Service Factor” is one of tolerance of adverse conditions, a built in “fudge factor” if you will. The conditions of use for SF will state that you can expect elevated motor temperature or words to that effect. When you run a motor from an inverter, THAT is also going to result in more motor heating, so you are ALREADY consuming that fudge factor, leaving you with nothing more.

You can’t have your fudge and eat it too…
Click to expand...
Ok.
SEWAG, my little pump motor that is water cooled and rarely loaded above .6HP was adversely affected in any way.
 
Status
Not open for further replies.
Top