Our website uses cookies to ensure a better performance and to measure page visits. Find out more about our use of cookies or how to change your settings, delete or turn off cookies at any time. Otherwise, we'll assume you're OK to continue with cookies in use. Accept

Electric Motor Electric Motor

Summary

  • Failure mode Overheating due to blockages and full bags.
  • Durability feature Longer brushes and auto-reset thermal switch. Sensors can also be built in.
  • Cost

Good practices

  • Good practicesAuto reset thermal switch
  • Good practicesLong brushes

Bad practices

  • Bad practicesReliance on non-resettable motor fuse
  • Bad practicesUnsuitable type of bearing

Key facts

  • 28% of vacuum cleaners failed to meet customers’ expectation of a 5-year lifetime.
  • Which? surveys show that the most common faults are loss of suction, blocked filters and brushes.

Icon key

  • Failure mode Failure mode
  • Durability features Durability features
  • Cost saving Cost saving
  • Low cost Low cost
  • Cost neutral Cost neutral
  • High cost High cost

Key failure modes

Early life

  • Motors will fail if they get too hot. Blockages or a full dust bag or cyclone cause motors to overheat.
  • Vacuum cleaners should be designed to reduce the risk of blockages, and avoid failures due to overheating by fitting auto-resettable thermal switches that cuts off power. Users may think that the power cutting off is due to a fault and may return the cleaner to the retailer. Clear instructions should reduce this.
  • Some vacuum cleaners are fitted with warning lights that are connected to sensors with control circuits which show if the bag is full, the cleaner is blocked, brushes are clogged, etc. The meaning of these indication warning lamps needs to be explained in instruction manuals.
  • Many electric motors are fitted with an internal thermal fuse which will open permanently if the motor overheats, but these are not resettable and the motor becomes unusable.

Later in lifetime

  • Bearings and carbon brushes will wear and eventually fail. Their lifetime should be specified to exceed the required lifetime of the vacuum cleaner and lifetime requirements should take into account heavy users.
  • Carbon brush lifetime is dependent on their length
  • Bearings can fail earlier due to incorrect choice of bearing type or due to poor quality construction. Specifying and choosing bearings is technically very complex, so the vacuum cleaner supplier should provide evidence from testing of durability

Specification for improved performance

The specification below provides the recommended improvements needed to improve product durability. They are ranked from bronze to gold based on the effectiveness of the change in improving durability, with bronze being the minimum and gold being the maximum.

Auto-reset thermal switch; specify motor lifetime; sealed roller bearings

  • Specify the inclusion of auto-resettable thermal switches.
  • Electric motor lifetime can be specified. EU Regulation 666/2013 on the eco-design of vacuum cleaners sets a mandatory minimum operational motor lifetime of 500 hours (from 1 September 2017). This is based on about one hour’s use per week. For a lifetime of 10 years, the motor will be used intermittently for 520 hours.
    Negative temperature coefficient (NTC) thermistors to be used.
  • Sealed roller ball bearings are a suitable type, but must be of good quality and design. Bearing tolerances and dimensions are defined by ABEC standards. Testing can be used to assess quality.

Specify minimum 650 hours of use

  • Heavy use may double the time the cleaner is used and so a minimum usage time of 650 hours could be specified.

Indicators, sensors and control circuits; Minimum usage 800 hours

  • Include indicators, sensors and control circuits that give users indications of full bags, blockages, etc. 

Testing to demonstrate performance

  • Operational motor lifetime measurement should use the method in Annex II of Regulation 666/2013:The vacuum cleaner shall run with a half-loaded dust receptacle intermittently with periods of 14 minutes and 30 seconds on and 30 seconds off. Dust receptacle and filters shall be replaced at appropriate time intervals. The test may be discontinued after 500 hours and shall be discontinued after 600 hours. The total run-time shall be recorded and included in the technical documentation. Air flow, vacuum and input power shall be determined at appropriate intervals and values shall, along with the operational motor lifetime, be included in the technical documentation.
  • Thermal switches should comply with safety standard EN 60335-1 Annex D.
  • Bearings should be tested at the same time as the motor lifetime measurement to ensure durability.
  • Examine bearing for wear or damage after test. The bearing should function as new after 500 hours testing (no damage and no sideways movement of the inner roller).

Cost implications

Improved reliability of components can reduce early returns and improve brand reputation which, in turn, can lower business costs and increase long-term sales.

To calculate overall cost savings for your business, use the WRAP cost/benefit analysis tool (currently in draft form and available on request).

Saving

Neutral

Longer brushes

Fit motor with longer carbon brushes to increase lifetime.

Low Cost

Auto-reset switch 

Fit a thermal switch to prevent damage to motor due to over-heating.

High cost

Sensors + PCB  with LED indicators 

Sensors and indicators with control circuits to show user why motor has stopped and when to empty bag, etc.