We have a hot tub retailer in a new tenant space in a building with a 3-phase 208V Wye service. Their show room hot tubs require 240V split-phase (center tap neutral - standard 1-phase power). We have proposed 3 - 208 to 240 isolation transformers with the center taps of each connected to the service neutral. Question is - can the H1s be connected to the adjacent transformers' H3s to form a Delta configuration and feed a single 3-phase panel (the preferred approach) OR must the high outputs of the transformers remain isolated and feed 3 independent 1-phase panels (the default approach)? My phasor diagram indicates it should be OK, however this is in no way a common configuration making me think there be an issue. I appreciate your feedback and welcome an explaination as to why the delta configuration will not work.
3-phase 208V Wye to 240V Delta w/ common center taps
- Thread starter dindremr
- Start date
- Status
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
If you connect the 240V secondaries into a delta configuration, you may not connect all (3) of the 120V 'center-taps' to a common point (i.e. service neutral or ground) at the same time. If you do you will create a short circuit. effectively you would be connecting the 120V into a wye and 240V into a delta at the same time.
kwired
Electron manager
- Location
- NE Nebraska
Is running the units on 208 volts going to cause any problem besides reduced wattage in the heating elements?
Isn't the motors and controls on most of these 120 volt and the heaters are the only 240 volt load in the unit? If so I would not be afraid at all to power them with 208 volt. Heating cycles will take a little longer - for a unit that is not really being used anyway just being displayed.
Isn't the motors and controls on most of these 120 volt and the heaters are the only 240 volt load in the unit? If so I would not be afraid at all to power them with 208 volt. Heating cycles will take a little longer - for a unit that is not really being used anyway just being displayed.
ptonsparky
Tom
- Occupation
- EC - retired
A buck/boost transform set up would work for each unit, but I see problems as new units are brought in and old shipped out. Someone would have to make sure the heaters were the only part of the tub getting the boost.
Opt for the 208 usage.
Opt for the 208 usage.
tryinghard
Senior Member
- Location
- California
This is where I'm at. The specs should say this anyway and if not call the manufacture I bet its not a problem
- Status