Page 4
SE-330
Neutral-Grounding-Resistor
Monitor
Rev.
9-A-112913
2.1.5.1 R
ELAY
K1 F
UNCTION
(S1)
Set switch S1 to K1 = TRIP to assign the trip function
to relay K1 and to activate switch S2. Relay K1 will
change state when a resistor-fault or ground-fault trip
occurs.
Set switch S1 to K1 = PULSING to configure relay K1
for pulsing operation. See Section 2.3.
2.1.5.2 T
RIP
-R
ELAY
M
ODE AND
T
RIP
M
EMORY
M
ODE
(S2)
Set switch S2 to select the operating mode of trip relay
K1. In the non-fail-safe mode, relay K1 energizes and its
contact closes when a trip occurs. The non-fail-safe mode
can be used to trip shunt-trip circuit breakers. In the non-
fail-safe mode, SE-330 trips are reset when supply
voltage is cycled.
In the fail-safe mode, relay K1 energizes and its contact
closes if there are no trips. Contacts open if there is a trip,
a loss of supply voltage, or a processor failure. In the fail-
safe mode, SE-330 trips are not reset when supply voltage
is cycled.
N
OTE
:
Switch S2 does not affect the operating modes of
relays K2, K3, and K4.
N
OTE
:
Switch S2 only affects relay K1 operating mode
when K1 is assigned the trip function (switch S1 set to K1
= TRIP). Switch S2 defines SE-330 trip memory
regardless of the switch S1 setting.
2.1.5.3 G
ROUND
-F
AULT
-T
RIP
L
ATCH
(S3)
Set switch S3 to select latching or non-latching ground-
fault-circuit operation. Non-latching operation defeats
ground-fault-trip memory. See Sections 2.1.5.2 and 2.4.
2.1.5.4 R
ESISTOR
-F
AULT
-T
RIP
L
ATCH
(S4)
Set switch S4 to select latching or non-latching
resistor-fault-circuit operation. Non-latching operation
defeats resistor-fault-trip memory. See Sections 2.1.5.2
and 2.4
2.1.5.5 S
ENSING
-R
ESISTOR
S
ELECTION
(S5)
Set switch S5 to the resistance of the sensing resistor. For
the ER-600VC and ER-5KV, select 20 k
. For the
ER-15KV, ER-25KV, and ER-35KV, select 100
k
.
Switch S5 sets the resistor-fault trip value and the V
N
TRIP
LEVEL range. See Section 2.1.3.
2.1.5.6 F
REQUENCY
(S6)
Set switch S6 to 50 or 60 Hz to tune the digital filter to
the line frequency of the monitored system.
2.1.5.7 S
PARE
(S7)
2.1.5.8 U
PGRADE
E
NABLE
(S8)
Set switch S8 to RUN for normal operation or to
UPGRADE to enable firmware upgrades. Changes in
switch S8 settings are recognized only when supply
voltage is cycled. Protection is disabled after supply
voltage is cycled with S8 in the UPGRADE position. See
Section 4.1.3.
2.2 C
ALIBRATION
The SE-330 measures the resistance change of the
NGR relative to the NGR-resistance value determined at
the time of calibration. Calibrate the SE-330 on new
installations, if the NGR is changed, or if the sensing
resistor is changed.
N
OTE
:
If the SE-330 is not calibrated and is supplied
from the load side of the breaker (non-fail-safe mode),
calibrate within 12 seconds of power-up or it may trip and
interrupt its supply.
The CALIBRATION push button is located behind the
access cover on the front panel, and it is recessed to
prevent inadvertent activation.
N
OTE
:
Calibration must be performed with the SE-330
connected to the sensing resistor and NGR of the installed
system.
To calibrate, press and hold the CALIBRATION push
button until the green CALIBRATED LED turns off and
returns to on (if the LED is already off, press and hold
until the LED turns on). Calibration takes approximately
two seconds. If calibration is not successful, a resistor-
fault trip occurs, the RESISTOR FAULT TRIP LED will
be on, the CALIBRATED LED will be off, and the
DIAGNOSTIC LED will flash the calibration-error code.
See Section 2.8.
If latching resistor fault (switch S4) is selected, the
calibration-error code flashes until RESET is pressed
even if the CALIBRATED LED is on.
The calibration value is stored in non-volatile memory.
2.3 P
ULSING
O
PERATION
If switch S1 is set to K1 = PULSING, pulsing occurs
when terminal 16 is connected to terminal 17. Relay K1
operates at a 50% duty cycle and cycle time is adjustable
from 1.0 to 3.0 seconds. When terminals 16 and 17 are
not connected, K1 is not energized and its contact is open.
Relay K1 can be used to control a contactor rated for
use at the line-to-neutral voltage. The contactor causes
changes in neutral-to-ground resistance by adding or
shorting portions of the NGR. See Section 3.5. Pulsing
ground-fault current appears as zero-sequence current
upstream from the fault.
Pulsing ground-fault current is distinguishable from
charging current and noise, and it can be traced with a
clip-on ammeter or current probe. If pulsing current is
detected on a cable or conduit, the fault is downstream.
Systematic testing allows faults to be located without
isolating feeders or interrupting loads. If the fault is on a
conduit system with a complex mix of cables and ground
points, the exact location of the ground fault may be
difficult to determine.
Stop pulsing when the fault is located.
