9 wire OEM squirrel cage motor vs. 12 split wire wye start delta run motor

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DA72

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Location
Gibbstown NJ
We got a replacement for a 9 wire squirrel cage motor 20 hp 480 volts(L1-1,L2-2,L3-3,4-7,5-8-6-9). US motors sent a replacement motor that is a 12 split wire wye start/ delta run. We do not have the capabilities at motor starter to wire this start/ run configuration. At first we wired it wye start, motor draw continuous 32 amps, well above FLA of motor. Which I now read improper hook up. Reading online (http://rammotors.com/Tech Tips/Wye Start - Delta Run 101/index1.htm).

Changed wiring to delta run, (L1-1-12,L2-2-10,L3-3-11,4-7,5-8,6-9). Upon starting amp draw is 150 amps drifting down to 19.8 amps after reaching full rpms 10-15 seconds.

My questions: Is a 12 split wire wye start/delta run motor a feasible replacement for a 9 wire wye delta motor?
Or will the High amp draw upon startup damage this motor after time?
If so is there a better wiring configuration?
 

just the cowboy

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Location
newburgh,ny
At 20 hp I don't see a need for Wye-start delta run

At 20 hp I don't see a need for Wye-start delta run

I would just keep it across the line, common for 20 hp.
 

infinity

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Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Does the motor nameplate wiring diagram depict something other than WYE start-DELTA run?
 

DA72

Member
Location
Gibbstown NJ
Does the motor nameplate wiring diagram depict something other than WYE start-DELTA run?

Wiring it high voltage(480), only has diagrams wye-start/delta run. I called the supplier and sales rep recommended the delta run wiring. The 150 amp starting current for the initial start 10-15 seconds has me concerned in time as motor ages will break down the insulation more rapidly then normal break down. I placed call to manufacturer and am still awaiting word on their recommendations.
 

don_resqcapt19

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Staff member
Location
Illinois
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retired electrician
We got a replacement for a 9 wire squirrel cage motor 20 hp 480 volts(L1-1,L2-2,L3-3,4-7,5-8-6-9). US motors sent a replacement motor that is a 12 split wire wye start/ delta run. We do not have the capabilities at motor starter to wire this start/ run configuration. At first we wired it wye start, motor draw continuous 32 amps, well above FLA of motor. Which I now read improper hook up. Reading online (http://rammotors.com/Tech Tips/Wye Start - Delta Run 101/index1.htm).

Changed wiring to delta run, (L1-1-12,L2-2-10,L3-3-11,4-7,5-8,6-9). Upon starting amp draw is 150 amps drifting down to 19.8 amps after reaching full rpms 10-15 seconds.

My questions: Is a 12 split wire wye start/delta run motor a feasible replacement for a 9 wire wye delta motor?
Or will the High amp draw upon startup damage this motor after time?
If so is there a better wiring configuration?
What kind of load is the motor driving? Does it take the 10-15 seconds for the motor to get up to speed?

There should be no issue using a delta connected motor in place of a wye connected motor assuming the horsepower is the same and the motor is wired correctly. I have never seen a wye/delta motor that could not be run across the line wired in the delta configuration, as long as the power source was stiff enough to start the motor.

How long did you run it wye connected?
 

electric_cal

Member
Location
California
We got a replacement for a 9 wire squirrel cage motor 20 hp 480 volts(L1-1,L2-2,L3-3,4-7,5-8-6-9). US motors sent a replacement motor that is a 12 split wire wye start/ delta run. We do not have the capabilities at motor starter to wire this start/ run configuration. At first we wired it wye start, motor draw continuous 32 amps, well above FLA of motor. Which I now read improper hook up. Reading online (http://rammotors.com/Tech Tips/Wye Start - Delta Run 101/index1.htm).

Changed wiring to delta run, (L1-1-12,L2-2-10,L3-3-11,4-7,5-8,6-9). Upon starting amp draw is 150 amps drifting down to 19.8 amps after reaching full rpms 10-15 seconds.

My questions: Is a 12 split wire wye start/delta run motor a feasible replacement for a 9 wire wye delta motor?
Or will the High amp draw upon startup damage this motor after time?
If so is there a better wiring configuration?

Your wiring configuration for this motor is correct. Have you considered installing a soft-start controller to help alleviate the high starting current and the duration of the start?
 

ActionDave

Chief Moderator
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Location
Durango, CO, 10 h 20 min from the winged horses.
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Licensed Electrician
Wiring it high voltage(480), only has diagrams wye-start/delta run. I called the supplier and sales rep recommended the delta run wiring. The 150 amp starting current for the initial start 10-15 seconds has me concerned in time as motor ages will break down the insulation more rapidly then normal break down. I placed call to manufacturer and am still awaiting word on their recommendations.
You're right, ten to fifteen seconds at 150A is too long but I agree with don_resqcapt19, something else is up.
 

kwired

Electron manager
Location
NE Nebraska
We got a replacement for a 9 wire squirrel cage motor 20 hp 480 volts(L1-1,L2-2,L3-3,4-7,5-8-6-9). US motors sent a replacement motor that is a 12 split wire wye start/ delta run. We do not have the capabilities at motor starter to wire this start/ run configuration. At first we wired it wye start, motor draw continuous 32 amps, well above FLA of motor. Which I now read improper hook up. Reading online (http://rammotors.com/Tech Tips/Wye Start - Delta Run 101/index1.htm).

Changed wiring to delta run, (L1-1-12,L2-2-10,L3-3-11,4-7,5-8,6-9). Upon starting amp draw is 150 amps drifting down to 19.8 amps after reaching full rpms 10-15 seconds.

My questions: Is a 12 split wire wye start/delta run motor a feasible replacement for a 9 wire wye delta motor?
Or will the High amp draw upon startup damage this motor after time?
If so is there a better wiring configuration?
You are not understanding the reason for wye start - delta run.

It is a reduced voltage starting method and the intention is to reduce the level of the initial surge in current when starting the motor - usually because of concerns over a large motor putting too much drain on the source during starting for various reasons. A 20 HP connected to a utility source is seldom ever using a reduced voltage starting method with exception of electronic soft starters provided for reasons related more to the driven load then to starting effects on the supply voltage.

If you have a 12 lead 240/480 volt motor you have two 240 volt rated coils per phase, and when you connect to a 480 volt supply you connect two 240 volt coils in series per phase across 480 volts and do so in a delta configuration. When doing this each individual coil sees its rated 240 volts.

When you connect those same coils of a 12 lead motor in a wye configuration and supply 480 volts you only have 277 volts from each supply lead to the common point of the wye, divide that by two because you have two coils in series in each phase and you only have 138.5 volts across each coil designed to operate at 240 volts.

This works to use it that way when starting with wye-delta starting method because the initial surge current will be much less, but you can only leave it connected that way for very short time (like a couple seconds max) and then you need to switch to delta connection so you are applying full rated voltage to each coil, or it will be under supplied and current will go up to try to compensate - which is why your motor is drawing high current. You pretty much have to use a "wye-delta starter" that automatically transfers from wye connection when starting to delta connection at the right time which becomes the run stage of the setup.

Bottom line is Wye-delta is an optional starting scheme, same motor will start directly across the line if leads are connected properly for full voltage application, but if supplied by a limited source may draw voltage down during starting. This is generally not a problem for the motor itself but is a problem for other loads that see that reduced voltage when this motor is starting.

Outside of when you have on site power generation that maybe has more limitations, Wye-delta or other reduced voltage starting methods are not usually seen until you get into the 100 Hp or higher motor sizes, But any 12 lead delta wound motor could easily be utilized for this starting scheme.
 

DA72

Member
Location
Gibbstown NJ
You are not understanding the reason for wye start - delta run.

It is a reduced voltage starting method and the intention is to reduce the level of the initial surge in current when starting the motor - usually because of concerns over a large motor putting too much drain on the source during starting for various reasons. A 20 HP connected to a utility source is seldom ever using a reduced voltage starting method with exception of electronic soft starters provided for reasons related more to the driven load then to starting effects on the supply voltage.

If you have a 12 lead 240/480 volt motor you have two 240 volt rated coils per phase, and when you connect to a 480 volt supply you connect two 240 volt coils in series per phase across 480 volts and do so in a delta configuration. When doing this each individual coil sees its rated 240 volts.

When you connect those same coils of a 12 lead motor in a wye configuration and supply 480 volts you only have 277 volts from each supply lead to the common point of the wye, divide that by two because you have two coils in series in each phase and you only have 138.5 volts across each coil designed to operate at 240 volts.

This works to use it that way when starting with wye-delta starting method because the initial surge current will be much less, but you can only leave it connected that way for very short time (like a couple seconds max) and then you need to switch to delta connection so you are applying full rated voltage to each coil, or it will be under supplied and current will go up to try to compensate - which is why your motor is drawing high current. You pretty much have to use a "wye-delta starter" that automatically transfers from wye connection when starting to delta connection at the right time which becomes the run stage of the setup.

Bottom line is Wye-delta is an optional starting scheme, same motor will start directly across the line if leads are connected properly for full voltage application, but if supplied by a limited source may draw voltage down during starting. This is generally not a problem for the motor itself but is a problem for other loads that see that reduced voltage when this motor is starting.

Outside of when you have on site power generation that maybe has more limitations, Wye-delta or other reduced voltage starting methods are not usually seen until you get into the 100 Hp or higher motor sizes, But any 12 lead delta wound motor could easily be utilized for this starting scheme.

Thank you kwired,
After reading multiple posts and speaking with USMotors. Many newer motors even lower HP motors such as the 20HP are replacing the 9 wire straight line with the 12 wire wye start/delta run motors. Wiring delta run is the proper connection for straight line motor replacement. Since my application only starts once a day the high inrush current won't be a factor or damage the motor. But should this motor start multiple times an hour, then a soft start or VFD would need to be added.
 

kwired

Electron manager
Location
NE Nebraska
Thank you kwired,
After reading multiple posts and speaking with USMotors. Many newer motors even lower HP motors such as the 20HP are replacing the 9 wire straight line with the 12 wire wye start/delta run motors. Wiring delta run is the proper connection for straight line motor replacement. Since my application only starts once a day the high inrush current won't be a factor or damage the motor. But should this motor start multiple times an hour, then a soft start or VFD would need to be added.
Soft start or VFD being necessary really has little to do with the fact the motor is delta connected, and in fact "soft starting" is sort of just a more modern method of "reduced voltage starting" which wye -delta starting is in fact a reduced voltage starting method.

If you do not use a wye delta starter on this motor you connect it per the "run configuration" and apply full voltatge at all times when running - AKA "across the line starting".

If you use a VFD or soft starter you still connect per run configuration and let the drive or starter handle the rest of voltage regulating.
 
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