Expected cause and effect to a 480v water pump motor(induction) supplied by 415v

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Mathew78

Member
Location
Melbourne
I was wondering if anyone could advise on cause and effect to a 480v water pump motor(induction) which supply voltage has been changed from 480v to 415v. Is it just that it will draw proportionately higher current?

The electricity network on the street has recently been upgraded from split phase (single phase transformer which converts 22kv [taken from 2 hv phases] primary to 2x 240v windings on the secondary, neutral being the middle tap to give either 240v 2 wire supply or 480v 3 wire) to 3 phase.

Also are these 480v pumps polarity specific ie if the rotation was changed on the street when it was upgraded from 2 hv cables to 3 would that change the direction of the motor, as if the 2 actives feeding the motor where switched around.

Thanks for any help.
 

LEO2854

Esteemed Member
Location
Ma
I was wondering if anyone could advise on cause and effect to a 480v water pump motor(induction) which supply voltage has been changed from 480v to 415v. Is it just that it will draw proportionately higher current?

The electricity network on the street has recently been upgraded from split phase (single phase transformer which converts 22kv [taken from 2 hv phases] primary to 2x 240v windings on the secondary, neutral being the middle tap to give either 240v 2 wire supply or 480v 3 wire) to 3 phase.

Also are these 480v pumps polarity specific ie if the rotation was changed on the street when it was upgraded from 2 hv cables to 3 would that change the direction of the motor, as if the 2 actives feeding the motor where switched around.

Thanks for any help.

Yes if the phases were reversed from the street it will change the rotation of the motors.


Is the supply 480 volts or is it 415 volts, that does not seem clear in the first half of your post.

Welcome to the forum.....:)
 

kwired

Electron manager
Location
NE Nebraska
If I understand correctly the service was initially single phase, which should mean you have single phase motors. You would have to physically change the relationship of connection of main and aux windings in the motor itself to make it run the other direction.

Whether or not the motor can take the change from 480 to 415 volts would depend on a few things. It will likely run but that doesn't mean it will not be stressed with this new supply and will end up shortening it's life.

One has to ask what the frequency is and whether or not it may have changed as well. 480 volts is typical voltage for 60 cycle 415 is typical for 50 cycle. Don't know what you have there or if there is a possibility for both frequencies. If the frequency did change - probably no harm at all to the motor - as it will still be operating in the same volts/hertz ratio - but will effect the performance of the pump as it will run slower.
 

AdrianWint

Senior Member
Location
Midlands, UK
If I understand correctly the service was initially single phase, which should mean you have single phase motors. You would have to physically change the relationship of connection of main and aux windings in the motor itself to make it run the other direction.

Whether or not the motor can take the change from 480 to 415 volts would depend on a few things. It will likely run but that doesn't mean it will not be stressed with this new supply and will end up shortening it's life.

One has to ask what the frequency is and whether or not it may have changed as well. 480 volts is typical voltage for 60 cycle 415 is typical for 50 cycle. Don't know what you have there or if there is a possibility for both frequencies. If the frequency did change - probably no harm at all to the motor - as it will still be operating in the same volts/hertz ratio - but will effect the performance of the pump as it will run slower.

The OP in Australia, which uses the 'British' system and is a 50Hz country.

I think the original supply that the OP had is what is known as a split phase supply here in the UK .... its 240V - 0 - 240V ... ie its single phase and much like the US 120V - 0 - 120V, also being derived by centre tapping a secondary winding fed from a single phase HV pair. The pump being wired between the two outside 'hots' but with 180 phase difference not 120 deg.

I think that the OP has 'upgraded' to a new 3 phase 415/240 WYE supply and is now asking if its OK to connect his pump (which expects to see 480V between the two 'hots' of his original supply) to his new supply which only has 415V between phases. The pump motor being single phase so wont change rotation.

The question is pretty much the same as the US 208V versus 240V debate but scaled up to our European voltages.
 

Mathew78

Member
Location
Melbourne
The OP in Australia, which uses the 'British' system and is a 50Hz country.

I think the original supply that the OP had is what is known as a split phase supply here in the UK .... its 240V - 0 - 240V ... ie its single phase and much like the US 120V - 0 - 120V, also being derived by centre tapping a secondary winding fed from a single phase HV pair. The pump being wired between the two outside 'hots' but with 180 phase difference not 120 deg.

I think that the OP has 'upgraded' to a new 3 phase 415/240 WYE supply and is now asking if its OK to connect his pump (which expects to see 480V between the two 'hots' of his original supply) to his new supply which only has 415V between phases. The pump motor being single phase so wont change rotation.

The question is pretty much the same as the US 208V versus 240V debate but scaled up to our European voltages.

Yeah well stated! So what you're saying is that single phase motors are not polarised ie doesnt matter if neutral and active (or in my case active and active) are swapped around, it will still spin in the same direction?

The rotation was half my concern the other half being what will be the effects of a the differnt supply voltage? Is it just a simple ohms law equation, meaning it will draw a little more current? Or are there other effects now that the vector angle has changed from 180 to 120 degrees?

Any ideas or opinions are appreciated.

Thanks

Thanks very much.
 

AdrianWint

Senior Member
Location
Midlands, UK
Yeah well stated! So what you're saying is that single phase motors are not polarised ie doesnt matter if neutral and active (or in my case active and active) are swapped around, it will still spin in the same direction?

The rotation was half my concern the other half being what will be the effects of a the differnt supply voltage? Is it just a simple ohms law equation, meaning it will draw a little more current? Or are there other effects now that the vector angle has changed from 180 to 120 degrees?

Any ideas or opinions are appreciated.

Thanks

Thanks very much.

To reverse a single phase motor, one must rewire the motor to alter the position of the internal capacitor - it cant be reversed simply by swapping over the two supply wires.

The vector angle isn't 'seen' by the motor - all it can see is the potential difference between two conductors ie. one sinewave, the fact that these two conductors happen to be two different phases of a 3 phase supply is irrelevant - all the motor can 'see' is the potential difference between the two wires - ie. the motor is single phase (it isn't two phase!)
 

GoldDigger

Moderator
Staff member
Location
Placerville, CA, USA
Occupation
Retired PV System Designer
If the motor was rated only for 480V 60Hz, then it will not saturate on 415V 50Hz, but it may overheat or deliver less than rated fullod power because of the higher current. The extra current at full load may trip standard overload protection, acting to protect the motor.
 

kwired

Electron manager
Location
NE Nebraska
The OP in Australia, which uses the 'British' system and is a 50Hz country.

I think the original supply that the OP had is what is known as a split phase supply here in the UK .... its 240V - 0 - 240V ... ie its single phase and much like the US 120V - 0 - 120V, also being derived by centre tapping a secondary winding fed from a single phase HV pair. The pump being wired between the two outside 'hots' but with 180 phase difference not 120 deg.

I think that the OP has 'upgraded' to a new 3 phase 415/240 WYE supply and is now asking if its OK to connect his pump (which expects to see 480V between the two 'hots' of his original supply) to his new supply which only has 415V between phases. The pump motor being single phase so wont change rotation.

The question is pretty much the same as the US 208V versus 240V debate but scaled up to our European voltages.

I agree with everything said here - was not sure of voltage/frequency but had a suspicion it may be same as European systems, especially when that 415 volts was thrown in the mix.
 

kwired

Electron manager
Location
NE Nebraska
To reverse a single phase motor, one must rewire the motor to alter the position of the internal capacitor - it cant be reversed simply by swapping over the two supply wires.

The vector angle isn't 'seen' by the motor - all it can see is the potential difference between two conductors ie. one sinewave, the fact that these two conductors happen to be two different phases of a 3 phase supply is irrelevant - all the motor can 'see' is the potential difference between the two wires - ie. the motor is single phase (it isn't two phase!)
Actually a single phase induction motor is realistically a two phase motor, but the second phase is made by a few different ways including use of capacitors, different inductive reactance in a main and aux winding or combinations of both, as well as the shaded pole motors which I guess are a variation of two windings with different reactance. All these motors have two windings that have current somehow put out of phase with one another which makes them "two phase" motors, though there is only single phase supplied to the motor. To reverse the motor you need to change polarity of one of the winding circuits in relation to the other winding circuit, doesn't matter which one you physically move leads for - you are effecting the relationship between the two windings either way. Just want to make it clear that changing leads to a capacitor only will not change rotation. I also agree the 120 volt phase angle is not seen by a single phase load, just the volts from one supply lead to the other.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
....The rotation was half my concern the other half being what will be the effects of a the differnt supply voltage? Is it just a simple ohms law equation, meaning it will draw a little more current? Or are there other effects now that the vector angle has changed from 180 to 120 degrees?

Any ideas or opinions are appreciated.

Thanks

Thanks very much.
Odds are greatly in your favour that the pumps will be okay.

The rotation won't change, they likely will draw more current but also likely will stay within tolerances.

Are these impeller pumps?
 

Mathew78

Member
Location
Melbourne
Odds are greatly in your favour that the pumps will be okay.

The rotation won't change, they likely will draw more current but also likely will stay within tolerances.

Are these impeller pumps?

Yeah they are impleller pumps.

Thanks for all those who have helped out, much appreciated.

Cheers
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
It's very odd for these to be 480V single phase motors that ended up in Australia. They exist, but are EXTREMELY rare even here in the US. I have only seen them on some far flung rural farms for grain drier blowers. In fact there is a small one on eBay right now that has the nameplate showing. On that nameplate, it specifically says it is 480V 1 phase 60 cycle, then it goes on to say it is 380-400V single phase 50 cycle.
__KGrHqYOKjoE6VEbSsbFBOw-_pKo_g__60_1.JPG
That follows the SOP on motor designs, so there would be no problem with it working now. I'd be more surprised that it has worked on 480V 50Hz up until now, not to mention the unlikely existence of 480V 50Hz in Australia. Everything I have seen on Australian standards says that the voltage has been 400Y230V since 1980, and it had been 415Y240V before that. Residential service was 240, now 230V single phase, all 50Hz. Your neighborhood may have been late to the party, but I seriously doubt you have some sort of isolated island of power generation.

I think it's more likely that although your motor nameplate may SAY it is 480V single phase, it is likely a motor from some piece of farm machinery imported from the US and someone scavenged it to use it on a pump. So your 480V 60Hz motor has been working just fine, as it should, on 415V 50Hz all along. In fact it might be, and has been, 3 phase all along, and you, mathew78, have misinterpreted what you are seeing, as indicated by you seeming to think the old service was 240V and 480V when used with a neutral...
The electricity network on the street has recently been upgraded from split phase (single phase transformer which converts 22kv [taken from 2 hv phases] primary to 2x 240v windings on the secondary, neutral being the middle tap to give either 240v 2 wire supply or 480v 3 wire) to 3 phase.
No offense, but none of that makes any sense. It's more likely that your local utility just replaced an aging service and you got back exactly what you had all along, but have been ASSUMING it was something different because of the nameplate on that oddball motor.

AAAAnyway, it's all irrelevant I think. No matter what it was, I'm betting that if you just hook it back up the way it was, it will work the way it has. If it's really a single phase oddball motor, it will not matter how you hook it up to 240V, it will run the same. If, as I suspect, this is a common 3 phase 480V motor and has been connected to 400V 3 phase for years, reconnecting it, if you didn't mark the conductors, gives you a 50-50 chance of it running backward. It will be hard to tell on a centrifugal pump, because it will still pump either way, just less if it's wrong. So if it is 3 phase, hook it up and observe the results. Then swap any two leads and observe it again under the same circumstances. The highest flow is the correct rotation.
 

kwired

Electron manager
Location
NE Nebraska
It's very odd for these to be 480V single phase motors that ended up in Australia. They exist, but are EXTREMELY rare even here in the US. I have only seen them on some far flung rural farms for grain drier blowers. In fact there is a small one on eBay right now that has the nameplate showing. On that nameplate, it specifically says it is 480V 1 phase 60 cycle, then it goes on to say it is 380-400V single phase 50 cycle.
View attachment 11838
That follows the SOP on motor designs, so there would be no problem with it working now. I'd be more surprised that it has worked on 480V 50Hz up until now, not to mention the unlikely existence of 480V 50Hz in Australia. Everything I have seen on Australian standards says that the voltage has been 400Y230V since 1980, and it had been 415Y240V before that. Residential service was 240, now 230V single phase, all 50Hz. Your neighborhood may have been late to the party, but I seriously doubt you have some sort of isolated island of power generation.

I think it's more likely that although your motor nameplate may SAY it is 480V single phase, it is likely a motor from some piece of farm machinery imported from the US and someone scavenged it to use it on a pump. So your 480V 60Hz motor has been working just fine, as it should, on 415V 50Hz all along. In fact it might be, and has been, 3 phase all along, and you, mathew78, have misinterpreted what you are seeing, as indicated by you seeming to think the old service was 240V and 480V when used with a neutral...
No offense, but none of that makes any sense. It's more likely that your local utility just replaced an aging service and you got back exactly what you had all along, but have been ASSUMING it was something different because of the nameplate on that oddball motor.

AAAAnyway, it's all irrelevant I think. No matter what it was, I'm betting that if you just hook it back up the way it was, it will work the way it has. If it's really a single phase oddball motor, it will not matter how you hook it up to 240V, it will run the same. If, as I suspect, this is a common 3 phase 480V motor and has been connected to 400V 3 phase for years, reconnecting it, if you didn't mark the conductors, gives you a 50-50 chance of it running backward. It will be hard to tell on a centrifugal pump, because it will still pump either way, just less if it's wrong. So if it is 3 phase, hook it up and observe the results. Then swap any two leads and observe it again under the same circumstances. The highest flow is the correct rotation.


Only place I ever see such a motor (single phase 480 volts) is on a particular center pivot irrigation system that is driven by hydraulics. They prefer to use a 15 Hp motor on the hydraulic pump, but if only single phase is available they have a 10 HP single phase motor (I think it is usually dual voltage 240/480) that they put on it. The service is always 480 volts though, never seen one connected to 240. All they lose with the 10 HP motor is the ability to move the system a little faster when moving it without pumping water, which is only a couple times a year when the system needs moved for planting and harvesting operations, when watering they almost never even need all 10 hp from the pump.
 
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