Comet BS-I / BS-A devices are switchable single-pole voltage detectors. They are designed to detect operating voltages clearly indicating the “voltage present“ or “voltage not present“ state.

The voltage detectors are provided with a built-in self-test facility which checks the function of the circuit including the contact electrode (comprehensive self-test function) before each use.

The turning knob is used to select between three nominal voltage ranges:
0: Off
1: 5 – 10 kV
2: 10 – 20 kV
3: 20 – 30 kV

For transportation purposes, the insulating element can be removed from the display unit with the contact electrode.

According to the German accident prevention standard DGUV Regulation 3 (Table 1c), the device is subject to maintenance tests with minimum intervals of at least 6 years.