Several people have posted a problem with their Wallpod starting to make a humming or (worse) a buzzing noise after some time of normal use.

This noise is almost certainly due to a small bit of debris stuck between the 2 laminated electromagnetic cores of the EVSE’s contactor.  These are bit like 2 'E' shaped chunks of laminated iron - one fixed and one spring-mounted - with a coil around the centre limb of the fixed core.  When the coil is energized, the spring-mounted core is pulled sharply (against the spring) and hard to meet the other laminated core.  Attached to the spring-mounted core are the contacts which are opened or closed according to the function of the contactor.

Curing the Rolec Wallpod EVSE Contactor Buzz

If a small bit of debris - a piece of swarf, plastic or grit, anything really - gets stuck to one of the mating faces of the iron cores, it acts like a fulcrum, allowing the cores to 'wobble' about relative to each other.  Add the 50Hz alternating current from the applied mains supply (that's current changing direction 50 times a second and, consequently, electromagnetic attraction happening one way and then the other at the same rate) and this tiny amount of wobble creates the buzzing.  If the coil were powered by DC power instead, there would not be any noise.

The second illustration (above) shows where this debris can get stuck - obviously the mating faces on the spring-mounted core are possible locations as well.

The solution is relatively simple.  

1.  ENSURE THE POWER IS OFF - Use a 'voltstick' or meter to confirm this before opening the EVSE case.  If you are in ANY DOUBT WHATSOEVER about your competence to repair this EVSE, DON'T DO IT and get a pro in.

2. With the case lid off, photograph the contactor and associated wiring so you know how it all goes back together again.

3. If you are lucky, the 'tails' of heavy wire which connect to the main contactor terminals will be long enough to allow you to simply remove the 2 (in the case of Rolec's contactor) screws holding the top half of the contactor body to the bottom half.  If not then you will have to disconnect the wires.

  1. 4.Examine the faces of the laminated cores very carefully for debris.  In my case, a piece of plastic less than 1mm across had got caught in the centre portion of the fixed core and had been squashed nearly flat.  It required the application of a screwdriver to un-stick it.  As Rolec say, hoover the inside of the contactor (don't loose the spring!) and inside of the EVSE box thoroughly and reassemble the contactor.  You should find it quiet again.

If you require a replacement contactor, please use the payment button below to order one. This is a 3 pole + 1 Aux (NO) rated at 32A with a 230VAC coil.

● Application: remote making & breaking circuits; protect circuit

      from over-load when assembling with thermal over-load relay;

      frequent start-up and control of AC contactor;

● Electric ratings: AC50/60Hz, 690V, up to 95A;

● Utilization category: AC-3, AC-4;

● Altitude: ≤2000m;

● Ambient temperature: -5℃~+40℃;

● Mounting category: Ⅲ;

● Mounting conditions: inclination between the mounting plane

and the vertical plane should not exceed ±5°;

● Standard: IEC/EN 60947-4-1.  IEC/EN 60947-5-1.

Out of Stock - £18 inc P&P

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