Three phase starter used for 1 phase motor

[Jpflex]

All we have at our company is 3 phase starters and the closest I have is a 3 phase 1/2 hp motor starter with what looks to be with an adjustable overload knob

The motor is a single phase 1/4 hp motor at 115 volts. The NEC FLC was 5.8 ampere

Is it proper to feed the three phase 1/2 hp (all we have but close size) motor starter from a 15 ampere time delay fuse to only L1 terminal of starter and exit T1 to motor

Then leave neutral unfused, not connected to starter terminals, but source neutral connected directly to motor neutral terminal?

 

[Jpflex]

Motor

 

[ptonsparky]

I'd switch both thru the starter, but that's me.

ETA.

Are you using a 3 phase motor to replace the single phase or visa versa?

 

[petersonra]

You can do it that way.

You will need to run the wire thru all three overload heaters though if it is an iec style overload.

 

[Eddie702]

And you have to be able to set the overload current on the starter to what you need for that motor. Usually 1 15 x motor amps. But this can vary with the motor service factor.

 

[Jpflex]

3 phase starter with its internal overload so yea I guess I would have to connect neutral to overload contacts in starter for single phase motor

 

[Jpflex]

And you have to be able to set the overload current on the starter to what you need for that motor. Usually 1 15 x motor amps. But this can vary with the motor service factor.

I sure hope so, there is a dial so I think so

 

[Jpflex]

You can do it that way.

You will need to run the wire thru all three overload heaters though if it is an iec style overload.

What does iec style mean? We have these old starters but I’m not as familiar with them

I guess leads 95 and 96 are overload and A1 A2 control side

 

[Jpflex]

I'd switch both thru the starter, but that's me.

ETA.

Are you using a 3 phase motor to replace the single phase or visa versa?

Single phase motor using 3 phase starter only.

 

[petersonra]

What does iec style mean? We have these old starters but I’m not as familiar with them

I guess leads 95 and 96 are overload and A1 A2 control side

Sounds like iec style.

 

[retirede]

3 phase starter with its internal overload so yea I guess I would have to connect neutral to overload contacts in starter for single phase motor

Not necessarily. You could route the ungrounded conductor through all 3 poles.

 

[jim dungar]

Not necessarily. You could route the ungrounded conductor through all 3 poles.

You would do this by using some small jumpers. For example:
Line in to L1,
Jumper T1 to T2
Jumper L2 to L3
T3 to motor.

 

[retirede]

You would do this by using some small jumpers. For example:
Line in to L1,
Jumper T1 to T2
Jumper L2 to L3
T3 to motor.

My thoughts exactly.

 

[Jraef]

You would do this by using some small jumpers. For example:
Line in to L1,
Jumper T1 to T2
Jumper L2 to L3
T3 to motor.

No, that doesn’t do it, it splits the current flow. It all needs to be in series.

• Line hot goes to L1
• Jumper T1 to L2
• Jumper T2 to L3
• Motor hot lead goes to T3
• Connect the neutral directly.

 

[retirede]

No, that doesn’t do it, it splits the current flow. It all needs to be in series.

• Line hot goes to L1
• Jumper T1 to L2
• Jumper T2 to L3
• Motor hot lead goes to T3
• Connect the neutral directly.

I disagree - read it again. The only difference in his and yours is the direction of L2 & T2 in the circuit. They’re still in series.

 

[jim dungar]

No, that doesn’t do it, it splits the current flow. It all needs to be in series.

• Line hot goes to L1
• Jumper T1 to L2
• Jumper T2 to L3
• Motor hot lead goes to T3
• Connect the neutral directly.

Your method requires long jumpers to be run top to bottom of the contactor and overload.
My method allows simple short jumpers between two nearby terminals.

 

[Jraef]

Your method requires long jumpers to be run top to bottom of the contactor and overload.
My method allows simple short jumpers between two nearby terminals.

Yes, but in yours, the current is slit, so the OL elements will never see the full current.

 

[jim dungar]

Yes, but in yours, the current is slit, so the OL elements will never see the full current.

You are seeing things wrong, there is no current split.

My wiring has all contacts in series.

 

[Jraef]

You are seeing things wrong, there is no current split.

My wiring has all contacts in series.

D'oh... you are right! I did read that wrong. I see what you mean by the jumpers being shorter.

 

[texie]

It think the OP needs to start with the basics of understanding how a full voltage starter works, what its purpose is, and all the control issues that come with it. In this day and age you also need to understand the differences and nuances between a NEMA VS IEC starter.