start up current for single phase motor

[biocars1]

I need a 230 volt single phase motor that has a low start up current draw. I have a Dayton that runs "at speed" using 8 amps, but the spects show a potential start up draw of 90 amps.( my meter shows 72 amps) I am trying to use a UPS as a backup, but my UPS can only take about a 20 amp spike, and thats it. Is there a motor out there that does not spike so high ?

 

[gcaudill]

You could try a NEMA design C or D, but they have poor running efficiency and power factor, if that is of concern. A VSD or soft starter with current limit may also be helpful.

 

[busbar]

UPSs and motors/high inrush don't mix too well. Long Shot: if you could get past stalling, how about experimenting with something unconventional, like 1ø autotransformer starting?

 

[biocars1]

would a Permanent Split Capacitor (PSC) motor be better. This is used to power a belt driven blower , so it needs very little start-up torque

 

[GGOSS]

Single phase auto-transformer starters as suggested by busbar have proven very useful in such situations, however it is important to get the connections correct.

Make sure the you control the run winding only as this maximise starting torque.

Regards,
GGOSS

 

[GusD]

biocars1

It may be very hard to stay under the 20 Amp UPS spike limitation regardless of the starting method you use.UNless you go down to a much smaller motor.
What about "Bypassing" the UPS during the start of this motor.A typical start under normal load will take but a few seconds.

GusD

 

[jbartos]

Suggestion: There are manufactured single phase motors with locked rotor amps LRA 5 or 6 times full load amps FLA. Check:

http://www.baldor.com

Baldor Catalog shows:
1.
1 hp single phase motor
winding no. 35-257
FLA 7.3A
LRA 45A
Type 3520L
3450 RPM
2.
10 hp single phase motor
winding no. 37X47
FLA 46A
LRA 260A
Type 3740L
3450 RPM