Transformer in circuit with extractor fan..

[pmx_super]

Hi,

I just unpacked a replacement transformer for some 12V halogen lighting in my bathroom.

Reading the instructions I noticed it said that it shouldn't be used in circuits with an inductive load (e.g. an ventilating fans) due to voltage spikes that can occur on switching.

I have an extractor fan that is switched on by the main light switch. Do you anticipate this causing problems, and if so is there a solution (besides disconnecting the fan)?

Thanks

 

[mapj1]

Voltage spikes can be mitigated by the use of a varistor accross L and N.
Other than laying in a separate feed, the addition of supression components like that is the most likely solution.

Or if the makers have a helpline call it, and ask them why they are selling something unsuitable for common UK mains situations, and what they suggest.

 

[Steve]

do household ventilation fans make that much of a spike? would it really be detrimental to this transformer?

 

[BJS_Spark]

Small vent fans probably don't cause much of a spike on their own and this would not damage the TX for the lights. I guess the instructions are concerned that multiple TX's and a fan may cause high enough inrush to trip MCB but still not likely.

 

[mapj1]

If it cant take normal mains borne glitches , is not really fit for purpose, and you have a case against the makers.

 

[breezer]

If it cant take normal mains borne glitches , is not really fit for purpose, and you have a case against the makers.

i understand what you are saying, but i do not agree, since they have already stated that it should not be used with inductive loads.

there are some lighting controlers that are not to be used with inductive loads, also some have to be derated if using an inductive load, i guess they are "covering all bases"

 

[kendor]

The instructions are merely stating do not connect an inductive load to the transformer, your fan is merely in parallel with the primary winding of the transformer and not it's output so no worries apart from making sure that the switch itself has a suitable rating to allow for the inductance it is switching.

 

[pmx_super]

Thanks for all the input.

The over-arching message I'm getting is that there is minimal risk so I could just wire it all up as per normal.. though i guess a 25p varistor covers me both ways.