When is the LT3100 needed?
Ventilation fans, pumps, large lamps and other equipment that has large currents usually make use of magnetic contactors to control them. In this case, the best companion would be the LT3100.
What are the unique aspects of the LT3100 when it comes to control?
The LT3100 can directly control a magnetic contactor without the need for an intermediary relay, and it can accept the feedback signals from the auxiliary output of the contactor, including its on/off status, trip/overload status and auto/local status.
When the auto/manual switch is in the local position, the LT3100 will automatically switch off the control relay.
When the auto/manual switch is returned back to the auto position, the prior state is restored.
When the contactor trips, the LT3100 will also automatically turn off the control relay, and will ignore any control D-Bus commands from central control as safety protocol.
How can one keep track of the status of the magnetic contactor from the remote digital switch?
The LED on the digital switches shows the status of the auxiliary contacts of the contactor, it does not show the control relay status. The LEDs will blink to indicate that control is now local or when the contactor has tripped.
When is the remote digital switch needed?
Most contactors are installed within the control panel which resides in the equipment room, for the operator this is extremely inconvenient, when they need to operate the equipment they would need to leave their post and go to the panel. Not only is this inconvenient, but it can also be hazardous. Having remote control is the better solution. Better yet, control can now even be automated with a scheduler.
It is also worth mentioning that having remote control means that there is also the possibility of multiple access, this is different from having a single central control system which allows access only from the central control itself.