To provide the sensor line open-circuit detection system, using the fire receiver, which can select a plurality of applied voltages by a terminating resistor varying in resistance value with the voltage of a sensor line and prevents an unnecessary current from flowing to the terminating resistor.
The sensor line open-circuit detection system has plural fire sensors S1-Sn and the terminating resistor Rt connected to the two-wire type sensor line Ls in parallel to one another, and applies a specific voltage to the sensor line Ls by a fire receiver Ra and measures a current flowing through the sensor line Ls to detect an open circuit of the sensor line Ls; and the fire receiver Ra is equipped with terminating resistor Rt1 and Rt2 which have different resistance values, voltage sources VS1 and VS2 which have different output voltages, and power source switching means SWa and SWb which select one terminating resistor and one voltage source and connect them to the sensor line Ls, and both the ends of the sensor line Ls are both connected to the fire receiver Ra.
KAWANO YASUYUKI
YAMAMOTO SHINTARO
TANAKA TOSHIAKI
SHIBATA KIYOSHI
TABUSE TOSHIAKI
UEDA TAKESHI
