Power Usage Calculations For An Industrial Control Panel

[rustydud]

[FONT=&quot]Hello everyone, and thanks in advance for viewing.[/FONT]
[FONT=&quot]I have an industrial control panel that is powering a VFD, pilot lights, relays, digital panel meters, and some other devices. There is one(1) power feed powering the panel: it is 460VAC, 3-phase from a motor control center (MCC) bucket.[/FONT]
[FONT=&quot]The panel contains the following:[/FONT]

• (1) VFD. It is 460VAC, 3-phase and is running a 20HP pump.
  
• (1) 500VA transformer for transforming 460VAC, 3-phase to 120VAC, 1-phase. A few loads in the panel are 120VAC, 1-phase.
  
• (1) 24VDC power supply that is powered by the aforementioned 120VAC, 1-phase. Several loads in the panel are 24VDC. 24VDC loads include pilot lights and digital panel meters.

[FONT=&quot]I know how much current / power each device draws - I have this information readily available.[/FONT]
[FONT=&quot]Suppose you are asked to calculate the power usage of this panel. I am looking for the proper method to do this. What is the proper method for calculating the power usage of this panel?[/FONT]

 

[don_resqcapt19]

It would be easy to calculate the maximum possible power usage, but without actual running load information and actual time the equipment is running there is no way to calculate the power usage.

 

[Besoeker]

[FONT=&quot]Hello everyone, and thanks in advance for viewing.[/FONT]
[FONT=&quot]I have an industrial control panel that is powering a VFD, pilot lights, relays, digital panel meters, and some other devices. There is one(1) power feed powering the panel: it is 460VAC, 3-phase from a motor control center (MCC) bucket.[/FONT]
[FONT=&quot]The panel contains the following:[/FONT]

• (1) VFD. It is 460VAC, 3-phase and is running a 20HP pump.
  
• (1) 500VA transformer for transforming 460VAC, 3-phase to 120VAC, 1-phase. A few loads in the panel are 120VAC, 1-phase.
  
• (1) 24VDC power supply that is powered by the aforementioned 120VAC, 1-phase. Several loads in the panel are 24VDC. 24VDC loads include pilot lights and digital panel meters.

[FONT=&quot]I know how much current / power each device draws - I have this information readily available.[/FONT]
[FONT=&quot]Suppose you are asked to calculate the power usage of this panel. I am looking for the proper method to do this. What is the proper method for calculating the power usage of this panel?[/FONT]

Is there a "proper" method.
The main load is the pump VSD. Making a guess at PF and efficiency that would be around 18.5 kVA. Add in your 0.5 kVA tranny and a little bit of margin and around 20 kVA would be enough.

You mention power usage. Do you actually mean energy usage?

 

[petersonra]

[FONT=&quot]Hello everyone, and thanks in advance for viewing.[/FONT]
[FONT=&quot]I have an industrial control panel that is powering a VFD, pilot lights, relays, digital panel meters, and some other devices. There is one(1) power feed powering the panel: it is 460VAC, 3-phase from a motor control center (MCC) bucket.[/FONT]
[FONT=&quot]The panel contains the following:[/FONT]

• (1) VFD. It is 460VAC, 3-phase and is running a 20HP pump.
  
• (1) 500VA transformer for transforming 460VAC, 3-phase to 120VAC, 1-phase. A few loads in the panel are 120VAC, 1-phase.
  
• (1) 24VDC power supply that is powered by the aforementioned 120VAC, 1-phase. Several loads in the panel are 24VDC. 24VDC loads include pilot lights and digital panel meters.

[FONT=&quot]I know how much current / power each device draws - I have this information readily available.[/FONT]
[FONT=&quot]Suppose you are asked to calculate the power usage of this panel. I am looking for the proper method to do this. What is the proper method for calculating the power usage of this panel?[/FONT]

There is no "proper" way to do what you are asking, like there is a NEC required way to make a load calculation. You can make a load calculation in accordance with UL508a or the NEC, but short of running it under normal operating conditions and measuring the actual power consumption there is no way to know what the power consumption will be.