Installing 12 VFDs in one control cabinet

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Fallriverbryan

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Fall River, Wi USA
Hi All
I have been tasked with assembling a Motor control cabinet controlling 13 motors, 12 with VFDs. Am looking for a solution to distribute 480 3ph to the individual components. What solution have you guys used in the past? Cost effective. Don't have room for a bus bar system. Any thoughts?
 
Fallriverbryan said:
Hi All
I have been tasked with assembling a Motor control cabinet controlling 13 motors, 12 with VFDs. Am looking for a solution to distribute 480 3ph to the individual components. What solution have you guys used in the past? Cost effective. Don't have room for a bus bar system. Any thoughts?
Click to expand...
I use these and run my motor wiring thru fuses or breakers https://www.wistexllc.com/media/cat...8eab33525d08d6e5fb8d27136e95/c/h/ch160_14.png

Sent from my Coolpad 3622A using Tapatalk
 
Fallriverbryan said:
Hi All
I have been tasked with assembling a Motor control cabinet controlling 13 motors, 12 with VFDs. Am looking for a solution to distribute 480 3ph to the individual components. What solution have you guys used in the past? Cost effective. Don't have room for a bus bar system. Any thoughts?
Click to expand...

What are you going to do about the heat that all of these VFDs generate enclosed in this cabinet?
 
tkb said:
What are you going to do about the heat that all of these VFDs generate enclosed in this cabinet?
Click to expand...
As soon as you say you don't have room for a bus bar system I'm immediately concerned for the heat in the panel as well. In addition, you MUST pay attention to the manufacturer's required clearances above, below and around the VFDs, it's critical for proper cooling. In that regard, slotted wire duct is an obstruction, regardless of the slots. So if your VFD says 4" of clear space above and below the drive, that is 4" to the wire duct. Heat load and clearances for cooling are the two most common mistakes made in putting VFDs inside of control panels.
 
cooling

cooling

Jraef said:
As soon as you say you don't have room for a bus bar system I'm immediately concerned for the heat in the panel as well. In addition, you MUST pay attention to the manufacturer's required clearances above, below and around the VFDs, it's critical for proper cooling. In that regard, slotted wire duct is an obstruction, regardless of the slots. So if your VFD says 4" of clear space above and below the drive, that is 4" to the wire duct. Heat load and clearances for cooling are the two most common mistakes made in putting VFDs inside of control panels.
Click to expand...


Looking at AC for the cabinet. definitely a lot of heat to disperse with that many
VFDs
 
Jraef said:
As soon as you say you don't have room for a bus bar system I'm immediately concerned for the heat in the panel as well. In addition, you MUST pay attention to the manufacturer's required clearances above, below and around the VFDs, it's critical for proper cooling. In that regard, slotted wire duct is an obstruction, regardless of the slots. So if your VFD says 4" of clear space above and below the drive, that is 4" to the wire duct. Heat load and clearances for cooling are the two most common mistakes made in putting VFDs inside of control panels.
Click to expand...

you mean they can't be installed immediately next to one another? :slaphead:

OP be careful of this, jraef is 100% right.

is my experience that a power distribution block would be simpler and cheaper than a bus bar system.

I would be concerned if these we going in a 4x cabinet or being located outside, but we don't know enough to tell us heat dissipation is an issue. We have no idea what size the VFD's are nor do we know the enclosure size or materials. If we are talking 12 drives at 480 in SINGLE PANEL and all running at the same time-i'm going to assume this is a panel for conveyors in a warehouse and most of the motors are anywhere from 1-5 horsepower. VFD's are typically 96% efficient with 4% of power being dissipated as heat. even with 12 5-horsepower drives we are talking ~2.0 kw heat loss. That's just over 6000 BTU. There are other heat losses in the panel, but this would be the most significant. I don't see half a ton of heat causing premature failure if a supply fan (with filter) and exhaust vent is installed on the panel.

you install an ac now you need to locate somewhere to drain the condensate line. an ac might not be avoidable if the panel is rated 4x.

edit: adding this link from thermaledge. you can input the estimated heat loss, enclosure size, material, location and the ambinet/desired interior temperatures. i'm almost certain you will get by fine with forced air.
 
Last edited:
Fallriverbryan said:
Have 73 HP in the cabinet.
Click to expand...

What is the cabinet's NEMA rating and dimensions (HxWxD)?
Is it made out of steel?
Located inside or outside?
If outside, direct sun or shade?
What is ambient temperature of room/area it is located?

Given:
VFD efficiency = 96%
Heat loss = 4%
1 Watt = 3.412 BTU/hr
12000 BTU/hr = 1 Ton

Find heat loss of 73 HP worth of VFD input:
73 HP X 746 Watts/HP = 54.5 kW
54.5 kw x 0.04 = 2.2 kW heat loss = 7,430 BTU/hr = 0.62 Tons
 
drktmplr12 said:
What is the cabinet's NEMA rating and dimensions (HxWxD)?
Is it made out of steel?
Located inside or outside?
If outside, direct sun or shade?
What is ambient temperature of room/area it is located?

Given:
VFD efficiency = 96%
Heat loss = 4%
1 Watt = 3.412 BTU/hr
12000 BTU/hr = 1 Ton

Find heat loss of 73 HP worth of VFD input:
73 HP X 746 Watts/HP = 54.5 kW
54.5 kw x 0.04 = 2.2 kW heat loss = 7,430 BTU/hr = 0.62 Tons
Click to expand...

Not bad, small bedroom window unit should work.
 
drktmplr12 said:
What is the cabinet's NEMA rating and dimensions (HxWxD)?
Is it made out of steel?
Located inside or outside?
If outside, direct sun or shade?
What is ambient temperature of room/area it is located?

Given:
VFD efficiency = 96%
Heat loss = 4%
1 Watt = 3.412 BTU/hr
12000 BTU/hr = 1 Ton

Find heat loss of 73 HP worth of VFD input:
73 HP X 746 Watts/HP = 54.5 kW
54.5 kw x 0.04 = 2.2 kW heat loss = 7,430 BTU/hr = 0.62 Tons
Click to expand...
Goodness gracious me! How much more complicated can you make it..............:D
A couple of decent sized fans would shift that.
 
Besoeker said:
Goodness gracious me! How much more complicated can you make it..............:D
A couple of decent sized fans would shift that.
Click to expand...

in my first post, i suggested a supply fan with exhaust vent :p get about 2000 cfm and control it with thermostat. unless its nema 4x, then you need air to air heat exchanger. and if its outside you have to take that into consideration.
 
Without getting into your A/C sizing issues (assuming you know how that works), it's still important to make sure the clearances are adhered to. I've seen control panels with VFDs in them where everyone ASSumed that because they had A/C units set for 70F, that they could crowd the VFDs in there. But they have been dead wrong, as in lots of dead VFDs, because obstructing the proper air flow resulted in swirls and eddies that allowed specific components to over heat inside of the drives.
Here's an example of a bad VFD panel design, a lot of these drives failed in the field, despite having an A/C unit set at 70F, because the spacing was not observed.
ICP with VFDs.jpg

How are you protecting the VFDs? A lot of small ones are now UL listed behind what are called Motor Protection Circuit Breakers (MPCBs), which are the IEC style Manual Motor Starters that have thermal and magnetic trips, like this:
140M_family_front1--large_312w255h.jpg
These type of devices have a "comb" bus bar system that distributes power to them on the line side, that takes up very little room.
ALBR140MCW452N.jpg
Then you would run wires from the MPCBs to each individual VFD input.
 
Jraef said:
How are you protecting the VFDs? A lot of small ones are now UL listed behind what are called Motor Protection Circuit Breakers (MPCBs), which are the IEC style Manual Motor Starters that have thermal and magnetic trips, like this:
View attachment 18742
These type of devices have a "comb" bus bar system that distributes power to them on the line side, that takes up very little room.
View attachment 18743
Then you would run wires from the MPCBs to each individual VFD input.
Click to expand...

i've seen these before, makes for a VERY clean install.
 
they make the comb style bus bars for class CC fuse blocks too. I use them on a regular basis.

you can also get power distribution style lugs for your circuit breakers. sometimes that comes in handy.

a lot depends on how much power you need to distribute.
 
Nema 1

Nema 1

drktmplr12 said:
What is the cabinet's NEMA rating and dimensions (HxWxD)?
Is it made out of steel?
Located inside or outside?
If outside, direct sun or shade?
What is ambient temperature of room/area it is located?

Given:
VFD efficiency = 96%
Heat loss = 4%
1 Watt = 3.412 BTU/hr
12000 BTU/hr = 1 Ton

Find heat loss of 73 HP worth of VFD input:
73 HP X 746 Watts/HP = 54.5 kW
54.5 kw x 0.04 = 2.2 kW heat loss = 7,430 BTU/hr = 0.62 Tons
Click to expand...

Cabinet is indoors. Just a type 1. Don't have ambient info but ASSuming <105f. Steel
 
Jraef said:
Without getting into your A/C sizing issues (assuming you know how that works), it's still important to make sure the clearances are adhered to. I've seen control panels with VFDs in them where everyone ASSumed that because they had A/C units set for 70F, that they could crowd the VFDs in there. But they have been dead wrong, as in lots of dead VFDs, because obstructing the proper air flow resulted in swirls and eddies that allowed specific components to over heat inside of the drives.
Here's an example of a bad VFD panel design, a lot of these drives failed in the field, despite having an A/C unit set at 70F, because the spacing was not observed.
View attachment 18744

How are you protecting the VFDs? A lot of small ones are now UL listed behind what are called Motor Protection Circuit Breakers (MPCBs), which are the IEC style Manual Motor Starters that have thermal and magnetic trips, like this:
View attachment 18742
These type of devices have a "comb" bus bar system that distributes power to them on the line side, that takes up very little room.
View attachment 18743
Then you would run wires from the MPCBs to each individual VFD input.
Click to expand...

Darn, Looks like what I wanted. Mounting MCCBs on DIN wiring thru Duct. Can you send me a link to a US supplier for your MPCBs?
I need to get these for the next one.

Side note: Cabinet is 60x72x12
 
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