Siemens 3RB22 Manuel De L'appareil page 33

5.2 Thermistor protection
Deactivation: If the TEST/RESET button is pressed while the control voltage
3ZX1012-0RB22-1AA1
The unit is delivered with deactivated thermistor protection. If the
unit detects a connected thermistor upon being switched on, the
thermistor is automatically activated. If the thermistor is removed,
the thermistor function must be deactivated by the user, otherwise
a fault signal will be output. The user test serves to check the
thermistor evaluation (activated/deactivated) status.
(A1/A2) is switched on, the THERMISTOR LED will light up.
Releasing the button within 3 s will deactivate the thermistor
function. This will be shown by the THERMISTOR LED flashing in
10 s intervals.
Notice:
To ensure reliable functioning of the short-circuit detection in the
thermistor circuit, the line resistance when the thermistor is short-
circuited must not exceed 10 Ω!
Operation
23