It is an Ingenex 3-24VDC 50V solid state relay 2A, output with resistance type fuse 50V 2A. The input control signal voltage for the relay module is: (the state of the 0-2.5V low-level relay OFF; the state of the 3-24V high-level relay ON).
It refers to a high-level trigger signal between the trigger terminal (IN) and the negative power supply forward voltage is usually triggered by the positive electrode and the power supply connected to a terminalTypes of trigger mode, when the trigger end of the positive electrode voltage reaches the voltage or triggered, the relay is energized.
It has the blue KF301 terminal is connected to the line of control.
1 x 1 Channel 3-24V Relay Module Solid State High-Level SSR DC Control DC with Resistive Fuse