I need to switch an AC fan by a DAQ board's analog output.
Here is the setup in my mind for the moment:
The DAC of the data-acquisiton board can output 0 to 10V DC and can deliver max 5mA current. When the relay is ON the mains will power an AC fan. Here is the fan: http://uk.rs-online.com/web/p/axial-fans/2781543/ According to the data sheet I assume the fan will drive less than 1A. So I'm planning to use the following solid state relay: http://uk.rs-online.com/web/p/solid-state-relays/0346895/ since the data-sheet says it can handle upto 10A.
I have couple of questions here:
1-) In the relay's data-sheet, there is a section on the input current range which is not fixed. So I want to be sure if DAC can supply enough current for this relay. Do I need a voltage follower between the DAC and the DC input of the relay?
2-) If I can manage to turn on and off the relay, would the switching action cause a sudden peak current and damage the fan motor? Is there a difference between turning on the power of the fan via the relay and via a manual switch? I think motor works quite ok with the manual switch. I'm just wondering if the relay's switching action might cause some harmful inrush currents for this fan motor.
3-) If I can achieve to turn on and off the AC fan succesfully by using the relay and DAC, is there a possibilty to sudden stop this motor as well? I mean I have seen a VFD AC motor speed controller which is controlling a 3-phase AC motor. There is a switch which powers on of and breaks that motor. This manual switch when switched for the "break" function motor very quickly stops rotating. Maybe it is the function of the VFD controller or the 3-phase AC motor itself and may not be applicable in my case. The reason I'm asking about this, when the fan is powered off it keeps rotating for long time until it stops.