ECN Forum Forums General Topics of the Trade General Discussion Area Septic System Controls & Pumps

Wolfgang, we do things a little diffeent here.

Our "220" volt circuits are created by using two 110 legs that are 'out of time' with each other; this contrasts to your use of a 220 leg with a neutral wire.

In our 208 three phase set-ups, we have three legs that are each only 120 to ground, plus a neutral. The 120 circuits are simply drawing from just one leg.

Where the actual three phase power measures out at 240, the individual legs will likely measure out as 120, 120, and 208 volts respectively. In that case, you must be vcareful as to which leg you take your 120 from!

@ renosteinke:
Thanks for the answer. I have already seen those schemes with transformers tapped in the midst of one leg. So I have no problem with the details given for the small installation in this thread, assuming the 2 hot wires are at 180° of a single phase transformer (or single leg):


but I wondered how does one provide 460V, 230 V and 115 V at the same time out of one transformer in three phases:

As all voltages are linked here by factor 2 and not 1.73, what is three phase here? Or is a second transformer involved?
Thnaks for your patience.

The "230, 460" portion will be 230 or 460 volt. The motors come with 9 leads, and the windings can be connected either in series or in parallel.

The "115" portion could be taken from the same transformer for the 230 volt system, however the "460" volt version would require the control voltage to be taken from another source.
I don't understand why they would want a "neutral" to be run with the 460 volt system, as this would provide 277 volt power.

The actual 3Ø system voltages are nominally rated as:
120/208 Wye
120/240 Delta
277/480 Wye
and although they are becoming less common, there are still some 240 and 480 delta systems out there that provide no "neutral" at all.

Now I got it, thanks a lot. Doesn't sound very "harmonized" yet.

The designer made an error on the plan. L1 and L2 are 230-volt single-phase, and L3 is 115-volt single phase. There is no 3-phase circuit. In two emails the guy still hasn't told me the amperage requirements for the two circuits.

This is like receiving a machine arrive in 15 parts with no installation instructions other than a print with who-knows-how-many errors in it.

I think this guy enjoys travel with all expenses paid by the customer.

Dave

I got some cut sheets for the pumps today, so maybe I'm being impatient. I'm still trying to find out if it's OK for the 230-volt pumps to run at 250-volts, or if I need to drop the voltage with a transformer.

Dave

Tiger, NEMA standards typically allow for + or - 10% of the rated voltage for motors. So running "230" motors on 250 volts actual should be fine.