[illflatliner]

Lets start out by saying I don't have much experience with services that have a 3 phase delta. I just installed a new 3 phase 400a service for a farm service company. They are going to knock down the old fertilizer plant that required the high leg. There is only one motor that I must reattach, and it is wired up for low voltage 208 3 phase, on a 208/460 motor one phase being high. The company would like the power provider to change the delta to 3 phase Y, so they will be able to use all the breaker space in their new panel, instead of having the panel 1/3 unusable. Will the motor still work or cause any adverse effects?

 

[JRaef]

Your post seems unclear and one important part is difficult to understand.

Lets start out by saying I don't have much experience with services that have a 3 phase delta. I just installed a new 3 phase 400a service for a farm service company.

3 phase 400A, but at what voltage?

They are going to knock down the old fertilizer plant that required the high leg.

So was the old plant 120/240 3 phase 4 wire delta with a center tap then?

There is only one motor that I must reattach, and it is wired up for low voltage 208 3 phase, on a 208/460 motor one phase being high.

That highlighted part makes no sense. Please clarify.

The company would like the power provider to change the delta to 3 phase Y, so they will be able to use all the breaker space in their new panel, instead of having the panel 1/3 unusable.

Unusable? You mean for 120V single pole circuits? Because it is still perfectly usable for 230V 2 pole or 3 pole circuits.

Will the motor still work or cause any adverse effects?

From what? If you are asking the utility for a 208Y120V service now, and the motor says it is 208V, then there would be no "ill effects" from that standpoint. If you have a 120/240V 4 wire Delta center tapped service, and the motor nameplate says 200V, then yes, it might be damaging. If you have that 240V 3P4W delta service and the motor says 230/460V, then no ill effects. If you have a 208Y120V service and the motor says 230/460V, then maybe, you would have to check with the motor mfr and/or understand more about the load that the motor is running.

 

[micromind]

If the existing service is 120/240 3Ø 4 wire ∆, and the new service is 120/208 3Ø 4 wire Y, then the vast majority of the time, 230/460 motors will work just fine.

You might need to change the heaters in the starters, depending on the 208 volt current stated on the motor nameplate.

You'll also have less starting torque, less breakdown torque (this is when the motor is so overloaded that it s speed drops quickly), and with the same load, it'll run slightly slower.

If the motor has a service factor of 1.0, it might not do well on 208. If it's 1.15 or higher, it'll usually do fine on 208.

What type of load is the motor driving?

How far is it from the panel?

HP?

Service Factor (SF)?

Wire size?

Does the nameplate state 230/460 or 208-230/460? And if it's 230/460, is there another place that states something like 'useable on 208 at XX.X amps'?

Once we get this info, we can tell if it'll be ok on 208 or not.

Rob