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SE-330HV Neutral-Grounding-Resistor Monitor
Rev. 5-M-101817
3.4 I
SOLATED
G
ROUND
C
ONNECTION
An isolated ground bed can prevent a ground potential
rise (GPR) from being transferred to remote equipment.
If the G terminals on the sensing resistor and the
SE-330HV are connected to an isolated ground, the
SE-330HV will be exposed to the GPR. If the GPR is
greater than the terminal-block rating, the SE-330HV
must be isolated from station ground and precautions
must be taken with the power supply and the trip contacts.
See Technical Note RG-1 “NGR Monitoring with Isolated
Ground Beds” at www.littelfuse.com/relayscontrols.
An alternate configuration which allows an SE-330HV
to be connected to station ground is shown in Fig. 20.
The SE-330HV monitors the series combination of the
NGR and the two ground beds. This configuration is
acceptable provided the series resistance of the NGR and
the ground beds is within the NGR calibration range and
ground-bed-resistance changes remain within the trip
range. See Section 6.1.
FIGURE 20. Simplified Isolated-Ground Connection.
