Hi,
I have a heating element (750w) that forms part of the pre-heating stage of a house ventilation system (takes the edge off incoming cold air).
The problem is that the switched supply (S1) that enables it (and the fan that forces the air) cannot handle the ~3 amps required to run the heater.
So, first thought was to use a relay or contactor to switch a fused 'live' to the heater when S1 is on. Problem is that S1 drives the fan motor directly and also controls fan speed by varying its voltage from 100V to 230V. This varied voltage would also be driving the input coil of the relay and I have not been able to find a standard relay or contactor that will switch reliably over such a wide voltage range.
This leads me to title of the post. Can I use a solid state relay for this application? There are some fairly beefy 25A ones available with input signal range from 90V to 280V AC. Seems like an ideal solution but I've never used one before so I'm not sure.
I gather they can get a bit warm but there is loads of space in the housing to add a heatsink so no problem there. Plus the required heater current is only 3A vs the 25A rating so may not even be needed.
Any pitfalls anyone can think of to this approach?
Cheers,
iep
I have a heating element (750w) that forms part of the pre-heating stage of a house ventilation system (takes the edge off incoming cold air).
The problem is that the switched supply (S1) that enables it (and the fan that forces the air) cannot handle the ~3 amps required to run the heater.
So, first thought was to use a relay or contactor to switch a fused 'live' to the heater when S1 is on. Problem is that S1 drives the fan motor directly and also controls fan speed by varying its voltage from 100V to 230V. This varied voltage would also be driving the input coil of the relay and I have not been able to find a standard relay or contactor that will switch reliably over such a wide voltage range.
This leads me to title of the post. Can I use a solid state relay for this application? There are some fairly beefy 25A ones available with input signal range from 90V to 280V AC. Seems like an ideal solution but I've never used one before so I'm not sure.
I gather they can get a bit warm but there is loads of space in the housing to add a heatsink so no problem there. Plus the required heater current is only 3A vs the 25A rating so may not even be needed.
Any pitfalls anyone can think of to this approach?
Cheers,
iep