The PGR-3100 indicates the presence of voltage on each
phase of a three-phase system. The LEDs on the panel
illuminate when voltage is present. When a ground-fault
occurs, the voltage on the faulted phase reduces to ground
potential, causing the LEDs for the faulted phase to dim
and the LEDs for the unfaulted phases to become brighter.
Ungrounded ac systems are required by the National
Electrical Code (NEC®) Article 250.21(B) and the Canadian
Electrical Code Part 1, Section 10-106 (2) to have ground
detectors, such as the PGR-3100, installed on the system.
External potential transformers (PTs) can be used to step
down system voltage, allowing the PGR-3100 to be applied to
any system voltage. PTs are not required for system voltages
up to 600 Vac. Also available mounted in NEMA 4 enclosure.