Littelfuse SE-330AU, Руководство пользователя

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Page 3
SE-330AU Neutral-Earthing-Resistor Monitor
Rev. 4-I-101817
FIGURE 1. Configuration Switches.
2.1.4.3 S
ENSING
-R
ESISTOR
S
ELECTION (S5)
Set switch S5 to the resistance of the sensing resistor. For
the ER-600VC, ER-5KV, and ER-5WP select 20 k
W
. For
the ER-15KV, ER-25KV, and ER-35KV, select 100 k
W
.
Switch S5 sets the V
N
TRIP LEVEL range. See
Section 2.1.3.
2.1.4.4 F
REQUENCY (S6)
Set switch S6 to 50 or 60 Hz to tune the digital filter to
the line frequency of the monitored system.
2.1.4.5 U
PGRADE
M
ODE
(S8)
The microSD™ card is used for firmware upgrades.
See Section 4.1.2 for upgrade instructions.
N
OTE
: An upgrade causes an SE-330AU restart and this
may cycle the output relays.
2.1.5 R
ESISTOR-
F
AULT
T
RIP
T
IME
The resistor-fault trip time can be adjusted from 12
(default) to 60 seconds using the SE-MON330 software or
via network communications.
2.1.6 R
ESISTOR-
F
AULT
T
RIP
L
EVEL
The resistor-fault trip level can be adjusted using the
SE-MON330 software or via network communications.
See Section 6.1.
2.1.7 G
EO-
M
AGNETIC
F
ILTER
A low-frequency earth current can be caused by the
Earth’s magnetic field and from charged clouds passing
overhead during a thunderstorm. In some rare conditions,
this can cause a false resistor-fault trip. Enabling the geo-
magnetic filter and increasing the resistor-fault trip time
can help counteract these effects.
A trip time of 30 seconds is recommended when the
geo-magnetic filter is enabled.
The geo-magnetic filter is disabled by default, but can
be enabled using the SE-MON330 software or via
network communications.
2.2 C
ALIBRATION
The SE-330AU measures the resistance change of the
NER relative to the NER-resistance value determined at
the time of calibration. When the resistance change is
greater than a threshold amount (500
Ω for 20-k Ω
systems, 2,500 Ω for 100-k Ω systems), a resistor-fault trip
occurs. Calibrate the SE-330AU on new installations, if
the NER is changed, or if the sensing resistor is changed.
The CALIBRATION 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-330AU connected to the sensing resistor and NER of
the installed system.
N
OTE
: Where used, coupling components for lockout
earth-fault protection devices must be disconnected from
the supply during calibration.
To calibrate, press and hold the CALIBRATION 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.
The SE-330AU may be calibrated remotely using
the SE-MON330 software with the USB interface or the
communications options.
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 CT D
ETECTION
The SE-330AU monitors the continuity of the CT
circuit. When an open CT circuit is detected for two
seconds, the SE-330AU will trip on earth fault and the
diagnostic LED will flash the CT-Detection-Error code.
See Section 2.8. The CT-Detection-Error code remains
until CT-circuit continuity is detected and RESET is
pressed. If supply voltage is cycled, earth-fault trip
indication is not reset but the CT-Detection-Error
indication is reset. CT-Detection-Error indication will
resume after two seconds if CT-circuit continuity is not
detected.