motobrewer
I'm no atheist scientist, but...
assume you configured the 419 for a setpoint of 52F and a deadband of 2F. in cooling mode (heating mode would just be reversed):
Cut in mode: the controller will trigger the the compressor (close the relay) at Setpoint + deadband, ie 54 degrees. It will release the compressor (open the relay) at Setpoint, 52F
Cut out mode: the controller will trigger the compressor (close the relay) at Setpoint, ie 52F. It will release the compressor (open the relay) at Setpoint - deadband, 50F
So, in Cut In mode you're cycling between 52 and 54F. In cut out mode you're cycling between 50 and 52. Some people will say, "well, that's crap, i want it to be 52F all the time." For one, I think the A419 will let you set a deadband as low as 1F, so you could do that, and two, in On/Off control you always have some deadband. It's adequate for fermentation control, and you're limited by the mechanical system (your freezer) in the fact that you don't want it to be cycling often. I think the A419 calls the deadband "Differential" or dIF in the menu system.
hysteresis refers to the fact that a thermostat control system state is dependent on its history. For example, in our thermostat above (assume cut in mode), if I were to say, "The current temp is 53F, is the compressor on or off?" You couldn't make that determination. Therefore, a thermostat (any on/off control system for that matter) has hysteresis.
Cut in mode: the controller will trigger the the compressor (close the relay) at Setpoint + deadband, ie 54 degrees. It will release the compressor (open the relay) at Setpoint, 52F
Cut out mode: the controller will trigger the compressor (close the relay) at Setpoint, ie 52F. It will release the compressor (open the relay) at Setpoint - deadband, 50F
So, in Cut In mode you're cycling between 52 and 54F. In cut out mode you're cycling between 50 and 52. Some people will say, "well, that's crap, i want it to be 52F all the time." For one, I think the A419 will let you set a deadband as low as 1F, so you could do that, and two, in On/Off control you always have some deadband. It's adequate for fermentation control, and you're limited by the mechanical system (your freezer) in the fact that you don't want it to be cycling often. I think the A419 calls the deadband "Differential" or dIF in the menu system.
hysteresis refers to the fact that a thermostat control system state is dependent on its history. For example, in our thermostat above (assume cut in mode), if I were to say, "The current temp is 53F, is the compressor on or off?" You couldn't make that determination. Therefore, a thermostat (any on/off control system for that matter) has hysteresis.
