Energy efficiency advice & tips
Motors, Pumps and Fans
Opportunities exist in most buildings and industrial plants (both new and old) to
reduce the electrical energy used (kWh) in motors by improving the efficiency of
the motor and its power transmission system and reducing the amount of work that
it provides. The following actions should be considered:
- Perform motor survey
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A survey is the first stage in the process of addressing improvements to the efficiencies
of motors and drives in pumps and fans. Before you can assess and prioritise energy
efficiency improvements in motor-driven systems, you need to prepare an inventory
of all applications. Conducting a survey to collect the necessary information will
record the actual configuration and operation of the equipment – which may not be
the same as its intended or designed configuration and operation.
- Reduce the operating time of motors whenever possible by improving control of motor
driven loads
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Motor-driven equipment is controlled in a number of ways. All motors can be switched
on and off manually at a local switch point or load centre. An 8kW motor turned
off for an hour a day could save approximately £200 per year.
Most motor-driven loads are switched on and off by an external signal that is part
of a planned control strategy. Where new sensors, relays and control strategies
are required, the payback time is usually less than a year.
- Install motor or drive-shaft speed controls to reduce motor input power
-
This involves the retrofitting of existing motor drives with Speed-controlled drives–
to match the motor power to the load and/or capacity control devices or methods
Controlling motor speed to match the load can be very worthwhile as a reduction
in 20% of motor speed can save up to 50% of the energy used.
- Always specify high efficient motors
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A high efficient rated motor used in place of a 50 kW basic motor could realise
savings of £800 per annum.
- Use direct drives rather than belt drives
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A 36 kW motor driving a pump directly, rather than via a belt, could save about
£600 throughout the year.
- Changing pulley ratios on fixed speed motors can lead to significant energy savings
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Slowing a motor down by simply changing the pulley ratio is very cost effective
for fixed speed motors and can often achieve paybacks in under a year. A motor taking
6 kW at 3000 RPM and costing 51p per hour to run could take less than 1 kW and cost
less than 7p per hour to run at 1500 RPM.
Energy Efficiency Grant Scheme for
VSD
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