Efficient drives cut restaurant power bills

An ABB Automation Tech (Drives and Motors) product story

Edited by the Engineeringtalk editorial team May 7, 2008

Fifty McDonald's restaurants across the country are now saving 50% on power bills for kitchen extractor fans with the help of ABB Inverter drives.

Fifty McDonalds restaurants are now saving 50% on power bills for kitchen extractor fans with the help of ABB Inverter drives.

Dave Holden, Project Manager, Restaurant Services, for McDonalds, says: "We were updating old equipment and realised we could reduce our carbon footprint by making large fans run more slowly".

Variable speed control was implemented on fan units with large 5.5kW motors.

These now draw about 2kW for most of the time, but have the capacity to boost extract volumes significantly at busy times.

"Variable speed control gives us the extraction volumes we need while cutting energy use" Holden said..

"We will also change our specifications to request variable speed control when new equipment is purchased".

ABB Drives Alliance member, Inverter Drive Systems (IDS) in Nottingham has been working with McDonalds for six years.

McDonalds was hoping to see 40% energy savings and less wear and tear on the fan, including soft start-up.

IDS' solution was 5.5kW ABB HVAC drives.

Blaise Ford of IDS says: "Using the drive's real-time clock, we made the fans run at full speed over the busy periods and at 80% speed at other times".

"This resulted in a 50% saving in energy".

"On some installations, a boost button allows the fan to be speeded up to its full extraction speed if needed".

"Another major benefit was the reduced fan noise that this drive method allowed, particularly important to McDonalds at night".

Variable speed control also cured a problem which was affecting the operation of cooking equipment in the kitchen.

In order to contain cooking smells within the kitchen area, McDonalds aim to supply 85% of the air it extracts through air conditioning plant.

High extraction rates was creating an imbalance that meant whenever an external door or window was opened, there was a rush of cold air into the kitchen, affecting the energy consumption of the equipment as it attempted to maintain its cooking temperature.

It also meant the air conditioning was working harder to maintain a comfortable temperature.

Reducing the fan speed has alleviated these problems.

Holden says: "The average 50% saving in electrical consumption across the restaurants was even greater in select locations that had oversized fan motors from the 1980s".

"As well as reduced utilities costs, we now have fewer operational difficulties with the kitchen equipment as a result of being able to balance the extract volume".

Another advantage for Holden of using the ABB/IDS solution was that the setup required no involvement from the restaurant management team.

The retrofit work was fitted in around the busy times in the restaurant to avoid disruption.

The fan would normally be fitted on one day and changed over in a quiet time the following day, such as mid-morning, or even on the same day when a standby fan was available.