humming transfer switch

7craneway wrote:
any advice on transfer switch humming all the time some times very loud..do they make a quite one???

JOKE: Teach it the lyrics....

Serious: First: Make sure it is the transfer switch and not something else like a converter mounted nearby.

Now: There are basically two types of transfer switches,, I have not "Confirmed" but I suspect that one type is "3 way transfer" NOTE that this is suspicion only. (I will have to research this later tody) but that does not matter.

The 3-Way would be Inverter (no other power source present) Generator (if present) or shore power IF present.

Mine is a 2 way (Shore/Generator) the inverter has its own transfer switch which is also 2 way.

Two way switches like mine, when SHORE POWER is being used, there is NO energy to the solenoids.. They do not HUM, they just sit there, Cool as the room around them.

If the generator is runnign power is sent to the solenoids.... They may HUMM or not (if they do I don't hear it) but that is the only time they have power.

3: way
If shore power is present one bank of solenoids pulls in,, Generator the other.. They may hum.

Why do they hum?
The solenoid has a metal Core, this core, around which the wire is wound, is made up of many thin layers of iron, you lay in a layer, coat with varnish, lay in another varnish, and another varnish, till you have the core built up to the size you desire.. over the years the varnish dries, hardens and flakes away, now the leaves can vibrate against each other.

The solution.. Well there are 3
1: (Easiest) replace the switch
2: (less costly) Replace the solenoids
3: (Requires an electronic technician/engineer, IE: ME)_ convert the feed to the solenoids to DC, that way they won't hum, Some disadvantages to this but it can be done, one advantage too. Requires modification of the switch, voids all warranties.