3 phase motor question,

[hobbeekid]

Is there any particular way of determining which is the high/delta leg on a sd10 motor? I was thinking about doing a little sd10 action for new years if I can get the right size generator....

[holler]

Motors don't have a high leg. The high leg is only on a 4 wire delta system and reads 208 to neutral.

Is your motor a 9 lead or three lead?

[kx250rider]

Both of my SD10s are dual voltage (240/480). There is a metal ID plate with the wire numbers and hookup to select the voltage. 9 wires from the motor windings total, but only 3 wires for power (no neutral) . They're to be connected to the appropriate combination of wires from the motor per the chart. If yours is missing or illegible, I can post it. If yours is missing the paper numbers on the wires, it may be a PITA to identify them

Charles

[JasonC]

Motors only "see" phase-to-phase, so whether it's 3-phase wye, 3-phase delta, or high-leg delta, grounded corner delta, etc... it's always 208v or 240v phase-to-phase across the lines. High-leg delta only has any relevance with phase to ground, as you don't want 208v running into your 120v appliance.

FWIW, high-leg delta is becoming obsolete, with many power companies refusing to provide anything other than 3-phase wye, and sometimes 3-phase delta connections, to keep load balance on their lines.

[Archon]

IF the siren motor has 3 wires it is single voltage wound if It has 6 wires its dual voltage delta wound if it has 9 wires it is dual voltage Wye wound.

I have had or have sirens that had all of the above combinations.

[holler]

Down here high leg delta is extremely common, is offered to all customers who want three phase. They are phasing out the three wire delta and corner ground setups in favor of 4 wire delta and wye.

They actually prefer 4 wire delta setups for most light 3 phase stuff because of the economics of an open delta bank.

[hobbeekid]

Well, the motor has three leads for it,I think it's set up like yours Charles, I can't remember if there's a diagram on it .I'll pull the thing out and take pics of it and post em shortly...

Thanks , Jeff

[JasonC]

Down here high leg delta is extremely common, is offered to all customers who want three phase. They are phasing out the three wire delta and corner ground setups in favor of 4 wire delta and wye.

They actually prefer 4 wire delta setups for most light 3 phase stuff because of the economics of an open delta bank.

Whoops, my error, I meant open delta is becoming less common, although apparently many power companies still use it, especially in rural settings.

[holler]

Yeah, a lot of the newer motors don't like the crappy phase angles and voltage imbalances that open delta has to offer.

[Hacksaw]

OK, you guys made me study up on open delta!

Another "El cheapo" way of cutting costs in power distribution is using single wire earth return, or SWER. You use the ground/earth as the return path. But, it's not too efficient, with soil conductivity greatly affecting this set up. And, there's stray current issues that come up.

http://en.wikipedia.org/wiki/Single-wire_earth_return

This is popular in rural parts of the US, Canada, & Australia.