[integrator]

Hello,

We are looking at installing a VFD drive for the condenser on a carrier unit. The original motors are rated at 3.5 each with the name plate of 5.5 FLA. We replaced the motors for the VFD application and found out that the motors are drawing 6.2 amps per motor. We put back in the original motors and bypassed the drive. We are still reading a current draw of 6.2 amp. We've had two contractors out and couldn't find anything wrong. We cleaned the condenser coils, checked the charge, and verified the blade pitch.

Has anyone ever seen something like this. The problem is we don't know if this has been an issue for a while etc..... Tried to contact Carrier, just got the run around.

Thanks

 

[heatingman]

New blades different from the old?

What are the OEM motors rated for?


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[Ml002]

The vfd and motors, are they from carrier as a kit? One vfd for both motors? Where are you taking the amp reading? Did you check how many hrz the motor is running at?

 

[integrator]

Hello,

The motors removed were 3.4 amps 3 phase 208V 60H 1 HP. The nameplate says 5.5FLA.

The second contractor said the blades were the correct ones for this unit.

The Carrier is 48TJE028 series 500QA.

 

[integrator]

The vfd and motors, are they from carrier as a kit? One vfd for both motors? Where are you taking the amp reading? Did you check how many hrz the motor is running at?

NO the VFD is a ABB and it controls both motors. When this project was started, the 1st contractor took the info from the motors and sized the ABB drive correctly. It was only when everything was installed it they find out the high amperage.

I didn't check the HZ.

 

[reeferrat]

Did anyone take an amp draw of the motors that were removed? Are the new motors dual voltage or just 208V? Are you reading the amps on the drive or a meter? If you're using one drive for both fans, I think the drive would show the amperage sum of the loads. That VFD has to be sized perfectly in order to work. I'm assuming you're going this route for low ambient control? Seems overkill if it's just a RTU

 

[Spitz]

Are the motors marked with a service factor.

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[Spitz]

Maybe SF-1.4?

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[VTP99]

Why didn't you just buy the MotormasterIII from Carrier ?

 

[Spitz]

Why didn't you just buy the MotormasterIII from Carrier ?

It would probably make for a more straight forward install. Who makes those 3 phase motormaster for carrier? I have some Airstack chillers with that drive in them minus the Carrier stickers. Can barely read the display anymore had 1 drive smoke. I personally like the ABBs the best they seem to be the most user friendly and best support.

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[Spitz]

Found it ACTech. Same as the 3phase carrier motor masters, same as the one in my Airstack chillers.

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[71CHOPS]

so, you removed the original motors, installed 2ea. new motors, and a single speed drive.

each motor was drawing 6 amps.

so, you removed the new motors, and drive......installed the original motors, and have 6 amps each on the original motors.



do you know what the original motor's amp draw was before you started changing things?

 

[3rdlaw]

just curious , what amp draw is the drive displaying at 60hz , secondly the your amps on the supply side of the drive should be less than what your drive is seeing . this is supposed to be one of the benefits of using the drive it show less to the power company . has the motor manufacture been contaced they should be able to tell with surety what kind of amp draws you should be seeing , are your phases balanced