There is an ongoing debate amongst my colleagues and I. Is it better to put VFDs near the top of your enclosure, or near the bottom? I have designed my panels like I read a book. Left to Right, Top to bottom. The VFDs being output side of the control panel, I put them on the bottom. I put the PLC near to the top. My thoughts are, you will likely need to access the PLC or view it more often than the VFDs, and I can isolate the voltage of the Motor Leads to the bottom of the panel, in lieu of bringing them to the top. BUT, the argument here is that since the VFDs produce heat, put them at the top to isolate the heat near the top. I counter that by if you put them on the bottom, the whole panel then can be used to dissipate heat. Not just the top. What are your opinions?

 

Very much in agreement with yourself - but is fairly subjective depending on circumstance.

"... the argument here is that since the VFDs produce heat, put them at the top to isolate the heat near the top"
And where does the heat go or does it just get hotter!

Large control transformers generally come hot and heavy - and stay at the panel base where they are easier to mount, heat rises reducing the need for an anti-condensation heater, and safer as supply voltages are down there with it.

In hot countries such as the middle east panels are fan vented or air-conditioned, still using basic principles as above.

 

I hope your discussion is very correct...!

In fact, it's advisable to mount below the middle level of Panel, if PLC need to be mounted in same panel.

So, the different voltage level of wiring can be segregated and routed properly to reach the panel out (Terminal blocks).

Importantly, the exhaust fan that mounted at below bottom / lower level of panel will helps in exhausting the inside heat due to VFD.

 

VFD on the bottom. The output wiring is going to be putting out a lot of RFI/EMI inside of the box. Even if you use shielded VFD cable, the small area where the shield must be peeled back to terminate will emit. It's good practice to reduce exposure of other wiring in the box to that interference as much as possible. Placing the VFD at the top will result in a lot of other wiring being near or crossing the VFD output cables.

 

By keeping in mind the heat theory, its recommended to install VFD's at top of panel. But here in your case when you are installing PLC in the same panel, I think you designed it perfectly fine.