Industrial control for HVAC systems — VFDs

What’s up everyone. Josh Kingsley here, your host for All Things Control by Eaton.

In this installment of What’s in the Trailer, we will look at an HVAC system for a commercial building like a hotel. The system is outfitted with variable frequency drives, which are applied to help manage HVAC functions in the most cost-effective way possible. Let’s explore what’s in the trailer.

Detecting temperature increases and reacting

We turn on the demo by touching the start button on Eaton’s XP 503 HMI screen. Now let’s assume that we are talking about Crestar Hotels in Phoenix, AZ. We are in the height of the summer and temps are rising fast on a particularly hot day. I’m going to place my hand on the temperature plate, to replicate the increase in the temperature in the hotel’s lobby. Eaton’s PowerXL DH1 HVAC variable frequency drive detects the increase in temperature and subsequently increases the speed of the fan. 

The VFD also turns on the definite purpose starter that activates the compressor, and then it turns on the HVAC enclosed starter which activates the condenser fan. This provides more air conditioning to the lobby to maintain the temperature set point and is a feature included in the DH1, eliminating the need for a separate controller which saves you time and money.

PowerXL DH1 fire safety features

But Crestar’s troubles don’t end there. Let’s assume now that a fire breaks out in the Crystal ballroom. When the fire alarm is pulled, the DH1 detects the fire in the building and goes into “fire mode.” This runs the fan in reverse at full speed to remove smoke from the room. It’s a fantastic safety feature that overrides all other signals and protective functions to the VFD other than the need to continue to remove smoke from the room, which ensures that people can safely exit the building.

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