Dual power point connection

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Mart_OB

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Hi,

My customer wants to use 2 VFD (not installed in the unit) powered by two differents power connection. Each VFD will supply 3 motors. I will provide the motor protection inside the main control panel for each motor.

The question:

Am I obligated to provide two disconnects inside the control panel or it could be only 2 splitter block.
The article 409.110 ask me to identify each incoming supply circuit, but I don't find something about the disconnects.

Thanks
 
Okay, I'll bite. What's a 'VFD'?


variable frequency drive?
volunteer fire department?
vacuum fluorescent display?

At least that's what google came up with. ;)
 
Mart_OB said:
Hi,

My customer wants to use 2 VFD (not installed in the unit) powered by two differents power connection. Each VFD will supply 3 motors. I will provide the motor protection inside the main control panel for each motor.

The question:

Am I obligated to provide two disconnects inside the control panel or it could be only 2 splitter block.
The article 409.110 ask me to identify each incoming supply circuit, but I don't find something about the disconnects.

Thanks
Click to expand...
Each VFD must have its own OCPD up stream, sized at 125% of the VFD's maximum input current. The decision to use a disconnect is arbitrary, but it's a very good practice and adding a disconnect device to fuses is cheap, or using a CB takes care of both anyway.

Each motor MUST have it's own disconnect device as well by the way, located within sight of the motor as per usual.
 
Normally, the VFD (Variable Frequency Drive) are protected with fast acting fuse (Type J) or circuit breaker specified by the VFD manufacturer.

I'm not sure about
Each motor MUST have it's own disconnect device as well by the way, located within sight of the motor as per usual.

Normally, we provide a control panel on the unit (HVAC unit)
All motor protectors, in my case manual motor starters (GV2 SquareD), are installed inside the control panel.

Can I presume that the manual motor starters are considered as a disconnect and they are located in sight of the motors?
 
Mart_OB said:
Normally, the VFD (Variable Frequency Drive) are protected with fast acting fuse (Type J) or circuit breaker specified by the VFD manufacturer.

I'm not sure about
Each motor MUST have it's own disconnect device as well by the way, located within sight of the motor as per usual.

Normally, we provide a control panel on the unit (HVAC unit)
All motor protectors, in my case manual motor starters (GV2 SquareD), are installed inside the control panel.

Can I presume that the manual motor starters are considered as a disconnect and they are located in sight of the motors?
Click to expand...
Yes they are. There are also exceptions to the "within sight" rule as well, I was speaking in generalities.
 
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