Solution for improved pump protection

By L Dutrieux, NewElec


Published in:

Electricity + Control, September 2015 (pages 16, 17)

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The company represented by the author was recently approached by management of a local Polymer plant who was seeking a solution for improving the protection method on its pumps as an inordinate amount of money was being spent on maintaining and replacing pumps and associated parts at a pace that seemed extraordinary. The existing protection relay was a dry cut motor protection product that sensed the motor load current and the current trip level was user-selectable. However, owing to the very small current differential between the full load and minimum load conditions, the product appeared to have difficulty in appraising the load condition.

Typically, a 3 kW motor running at 380 Vac, if operated at full load, would result in a load current of 6 A. However, the actual full load condition at the plant is usually in the vicinity of 3 to 3,5 A. The measurement of the load current is made even more difficult by the HCL medium that is prone to forming gas bubbles at certain pressures and is also affected by ambient temperature. It seemed that it would be necessary tore-evaluate the protection protocol and make ready for a more futuristic approach that would incorporate both an improved and more modern protection concept.


Take note

  • Why wait for a failure before you replace the old equipment?
  • Understanding your system permits better protection and monitoring.
  • Proper preventive maintenance saves you time and money.