PGR-6101 Ground-Fault & Insulation Monitor Page 1
Rev. 0-C-041918
1. GENERAL
The PGR-6101 Ground-Fault & Insulation Monitor can
detect a motor ground fault whether the motor is running
(Online mode) or stopped (Offline mode), and can be used
to protect a motor supplied by a solidly grounded,
resistance-grounded, or ungrounded system. On an
ungrounded system, use only the Offline mode.
On grounded systems, a current transformer(CT) is used
to detect ground-fault current as low as 30 mA when the
motor is running, and insulation resistance is measured to
detect a fault when the motor is stopped. Online or Offline
mode is selected with a digital input connected to a starter
auxiliary contact.
In the Online mode, ground-fault current is sensed by a
PGC-5000-series zero-sequence CT. The trip level of the
ground-fault circuit is selectable from 30 to 200 mA. Trip
time is selectable from <50 to 250 ms. Additional current-
detection features include harmonic filtering, a relay output
that can operate in the fail-safe or non-fail-safe mode, CT-
connection detection, LED trip, power, and open-CT
indication, autoreset or latching trips with front-panel and
remote reset, a test button, and a 0- to 1-mA-analog output.
In the Offline mode, insulation-resistance monitoring is
enabled, with a selectable 60- to 600-kalarm-setting
range. Additional insulation-monitoring features include a
relay output that can operatein the fail-safe ornon-fail-safe
mode, LED active and low-resistance indication, and a 0-
to 1-mA-analog output.
The PGR-6101 can be directly connected to a supply up
to 1.3 kV. For systems from 1.3 to 5 kV, use a
PGH-5000 High Tension Coupler. For systems from 5 kV
to 6 kV, use a PGH-6000 High Tension Coupler.
2. OPERATION
2.1 OUTPUT RELAY OPERATING MODE
In the fail-safe mode the output relays energize when
power is applied and the ground-fault and insulation-
resistance circuits are not tripped. Fail-safe mode is the
factory setting.
For non-fail-safe operation connect terminals 19-20 and
22-23. The respective output relay will energize when a
fault occurs. See Fig. 2.
2.2 PGR-6101 OPERATING MODE
Connect terminals 27 and 28 to a normally closed (Form
B) auxiliary starter contact. When terminals 27 and 28 are
open, Online mode (insulation monitoring off) is selected
and when terminals 27 and 28 are connected, Offline mode
(insulation monitoring active) is selected.
2.2.1 ONLINE OPERATION
When the monitor is running, the PGR-6101 in
conjunction with a PGC-5000-series zero-sequence current
sensor operates as a sensitive ground-fault relay.
2.2.2 OFFLINE OPERATION
The PGR-6101 changes mode by means of an auxiliary
contact on the main contactor when the motor is off. It
becomes an insulation-resistance monitor and imposes a
small dc voltage to the motor windings and supply cable
from the motor starter. Leakage to ground is detected.
2.3 FRONT-PANEL CONTROLS
2.3.1 GROUND-FAULT TRIP LEVEL
The Leakage Current I selector switch is used to set the
ground-fault trip level from 30 to 200 mA. For ground-fault
detection, the switch setting must be set substantially below
the prospective ground-fault current. To avoid sympathetic
tripping, the switch setting must be above the charging
current of the protected feeder.
2.3.2 GROUND-FAULT TRIP TIME
The PGR-6101 has a definite-time trip characteristic. In
tripping systems, the TIME DELAY selector is used to set
the ground-fault trip time for coordination with upstream
and downstream ground-fault devices. Trip time is
selectable from < 50 ms to 250 ms. Coordination requires
the same trip level for all ground-fault devices in a system
and the trip time to progressively increase upstream. The
amount of equipment removed from the system will be a
minimum if the first ground-fault device to operate is the
one immediately upstream from the fault.
2.3.3 INSULATION RESISTANCE RESPONSE
The PGR-6101 insulation resistance function has an
adjustable alarm range of 60 to 600 k.There is no
selectable time delay. The unit will operate in less than
three seconds.
2.3.4 RESET
The front-panel RESET button is used to reset latching
trips. After a fault has been cleared, cycling the supply
voltage will also reset the PGR-6101.
To usethePGR-6101 inautoresetmode, connect terminals
18-19 and 21-22. See Fig. 2.
The reset function is not instantaneous. Press the RESET
button for several seconds.
