I do not put VFDs in cabinets at all - use masses of them. The ones we use are IP66 and they go on a stick alongside the motor - you can hose them safely. This means you only have to use a metre or so of that very expensive shielded cable as well. As much of my work is swimming pools everything has to run on a 30ma RCD - people in water. The drives I use are Australian designed and made and have a low loss filter system. I have 75kW drives running on 30ma RCDs.
PLC panel standards
- Thread starter Ltpriyank
- Start date
alive15
Member
Add an external port for ethernet / rs-232 communication between laptop and plc, so programmers won't have to open cabinet doors to work on PLC or other devices.
What do you do for arc flash protection?
The drives are totally enclosed in metal boxes - IP66. The cooling fan is external and blows over a large heat sink. Have never seen an arc come out of one yet but really where we use them arc flash protection is not really needed - nor in most installations. Rare to see it in Oz except in large switch boards (high current). And mines and the like.
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I've used similar drives in the past. One of the reasons I don't use them all of the time is because most customers also want a line reactor for the drive - and I haven't found an IP66 line reactor yet (doubt I ever will).
When I do use the drives separate - those under 5HP or so are candidates for Turck motor cables - which count as a disconnect. For those larger, there is often a disconnecting means near the motor (by code) or, for some drives, on the VFD itself. There is rarely (if ever) a need to open the VFD while the power is on.
busarider29
Lifetime Supporting Member
Use some sort of "wire retention" method inside the wire ducts. Nothing I can't stand more when it comes to electrical panels is when I pop the cover off of a wire duct and all the wires come falling out all over the place. 
They make components specifically for wire retention inside the wire duct, but you can also easily devise your own. I use a zip tie mount like this inside the wire duct, then a zip tie loosely around the wires bundles. Stagger every 8-10 inches throughout the wire ducts. DO NOT TIGHTEN DOWN the zip ties. Cut off the ends of the zip ties so that they can't be pulled down tight. I actually install these before I ever start running and terminating wire.
They make components specifically for wire retention inside the wire duct, but you can also easily devise your own. I use a zip tie mount like this inside the wire duct, then a zip tie loosely around the wires bundles. Stagger every 8-10 inches throughout the wire ducts. DO NOT TIGHTEN DOWN the zip ties. Cut off the ends of the zip ties so that they can't be pulled down tight. I actually install these before I ever start running and terminating wire.
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busarider29
Lifetime Supporting Member
Put cabinetry lighting inside the panel. Use LED, not florescent. Have the lighting turn on/off via a switch when the cabinet door is open and closed.
Wires: Label the wires so that the labels read top-to-bottom, or left-to-right when the wire is terminated.
Use crimp ferrules on all wires, where feasible.
Cabinet cooling: Have incoming cooling air fan at the bottom side, and outgoing exhaust vent on the opposite side, top of the panel.
Wires: Label the wires so that the labels read top-to-bottom, or left-to-right when the wire is terminated.
Use crimp ferrules on all wires, where feasible.
Cabinet cooling: Have incoming cooling air fan at the bottom side, and outgoing exhaust vent on the opposite side, top of the panel.
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Use some sort of "wire retention" method inside the wire ducts. Nothing I can't stand more when it comes to electrical panels is when I pop the cover off of a wire duct and all the wires come falling out all over the place.
They make components specifically for wire retention inside the wire duct, but you can also easily devise your own. I use a zip tie mount like this inside the wire duct, then a zip tie loosely around the wires bundles. Stagger every 8-10 inches throughout the wire ducts. DO NOT TIGHTEN DOWN the zip ties. Cut off the ends of the zip ties so that they can't be pulled down tight. I actually install these before I ever start running and terminating wire.
I have seen wire retention done with nothing more than what looked liked strong cotton, very thin, but quite strong. Wrapped tightly around the trunking side splines, with some looseness across the valleys. I've also seen elastic bands used ...
Yep, anything to stop the whole lot falling out is a good thing. Don't think you need to worry about vertical runs though ....
Don't you think the manufacturers could incorporate flexible "fingers" spanning the gap ? Surely possible ....
Most natural for me is bottom-to-top, no issues with left-to-right. Although some say wires should be labelled working away from the termination ! That would have them upside-down 50% of the time, but if that's a recognised convention, what's the problem?
There is not a "one size fits all" method for cabinet cooling. Your sweeping statement imposes a restriction on component/module placement, because the top of the cabinet will always be the hottest point. You will then have to consider what devices go where in that temperature gradient.
Over ventilating to compensate is just using excess energy.
In some extreme cases more than one, isolated, ventilation system may be required. Think about it, you would never locate load bank or dynamic braking loads in the same cabinet as the drives.
busarider29
Lifetime Supporting Member
busarider29
Lifetime Supporting Member
My theory with wire labels is have them read like a book binder. When the book is stood up vertically, you don't have the binder label reading from bottom-to-top, do you? Then it would be upside down, correct? Why would one treat a vertical wire label any different?
You do have a valid point here. In most cases though, the cooling and proper air flow of the panel as I described works. There are always exceptions though.
My theory with wire labels is have them read like a book binder. When the book is stood up vertically, you don't have the binder label reading from bottom-to-top, do you? Then it would be upside down, correct? Why would one treat a vertical wire label any different?
You do have a valid point here. In most cases though, the cooling and proper air flow of the panel as I described works. There are always exceptions though.
I can see a correlation to book-binders, the couple of books I have do read top-to-bottom. But then I looked at my DVD collection, and about half read bottom-to-top, the others read top-to-bottom. So standardisation never took hold there.
The cooling you described only works because you are over-cooling, and perhaps you need to think about the temperature gradient the heat-producing components will create.
Specifications of the devices will tell you min and max operating temperature ranges, so you need to use these for panel layout.
Sometimes panels need to be split into compartments and cooled, if necessary, in a different fashion. Same goes for heating, if a panel needs it.
There is more to panel design than just making it look nice ....
What do you think about using modules like this instead terminals on the very bottom of the panel?
This saves space and time necessary to wire something twice(from cable to terminals and from terminals to PLC), its easy to replace and modify. + and - distribution modules can be added as busbar on the side.
This saves space and time necessary to wire something twice(from cable to terminals and from terminals to PLC), its easy to replace and modify. + and - distribution modules can be added as busbar on the side.
We use exactly the same.
If the brand of wire duct do not have these retainers, a trick is to cut the covers into sections not longer than 30 cm or so. Instead of having to open a whole duct of a meter or more, you only open the section that you need access to. The wires will be much less prone to fall out. Obviously you need a cutter for the covers that make clean straight cuts. Otherwise it will look a bit naff.
Regarding the placement of VFDs.
VFDs generate heat and are also heat sensitive themselves. They may be rated to be able to sustain a high temperature, but that doesnt mean that you can operate them 100% at the highest rated temperature. Any VFD will be derated if it isnt operated at the 'nominal' temperature, typically 40°C.
Because of that, it makes sense to place VFDs at the bottom. If there are temperature sensitive components in the same enclosure it may be necessary with additional circulation or even cooling. If possible, place VFDs and PLCs in separate panel compartments.
Another thing is that it is the most convenient to terminate the motor cable directly at the VFD. Usually the cable screen can be terminated on the VFD chassis. That also speaks for placing the VFD at the bottom.
VFDs generate heat and are also heat sensitive themselves. They may be rated to be able to sustain a high temperature, but that doesnt mean that you can operate them 100% at the highest rated temperature. Any VFD will be derated if it isnt operated at the 'nominal' temperature, typically 40°C.
Because of that, it makes sense to place VFDs at the bottom. If there are temperature sensitive components in the same enclosure it may be necessary with additional circulation or even cooling. If possible, place VFDs and PLCs in separate panel compartments.
Another thing is that it is the most convenient to terminate the motor cable directly at the VFD. Usually the cable screen can be terminated on the VFD chassis. That also speaks for placing the VFD at the bottom.
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