Littelfuse SE-330AU, Руководство пользователя

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Page 2
SE-330AU Neutral-Earthing-Resistor Monitor
Rev. 4-I-101817
•
When the trip level is set to MEM, the earth-fault trip
setting is defined by an internal non-volatile memory
variable. Range is 2 to 100% in 1% increments of the
CT-primary rating.
•
Indication relays can be set to fail-safe or non-fail-
safe.
•
The number of trip records has been increased to 100
and includes date and time stamping.
•
A microSD™ card interface can be used for long-
term data logging and firmware updates. A
microSD™ card and a microSD-to-SD adapter is
included. See Section 4.1.
•
For ease of connection to new devices, the RS-232
interface has been replaced by a Mini B USB port.
•
Dual Ethernet ports are available with support for
fiber-optic and RJ45 interfaces.
•
The IEC 61850 protocol has been added.
2. O
PERATION
2.1 S
ETTINGS
2.1.1 EF T
RIP
T
IME
EF TRIP TIME (definite time) is adjustable from
0.1 to 0.5 seconds. Time-coordinated earth-fault protection
requires this setting to be longer than the trip times of
downstream earth-fault devices.
A trip-time accumulator provides an earth-fault memory
function for detection of intermittent faults. The
accumulated time increases when an earth fault is detected
and decreases when an earth fault is not detected. A trip
will eventually occur when the time for fault current above
the trip level is greater than the time for fault current below
the trip level.
2.1.2 EF T
RIP
L
EVEL
The SE-330AU uses a Discrete-Fourier Transform
(DFT) Algorithm to measure the fundamental component
of NER current.
Choose an NER let-through current and an earth-fault
trip level according to the guidelines in Section 1.1.
Earth-fault current is sensed by a sensitive CT (EFCT-x
or SE-CS30-x). The trip level of the earth-fault circuit is
adjustable from 0.125 to 5 A for the EFCT-x and 0.75 to
30 A for the SE-CS30-x.
When EF TRIP LEVEL is set to MEM, the earth-fault
setting stored in non-volatile memory is used. This
parameter must be set using a PC running the SE-MON330
software connected to the USB interface. The setting range
is 2 to 100% of CT-primary rating in 1% increments. For
example, if the MEM parameter is set to 15% (default), the
trip level will be 0.75 A or 4.5 A when using the EFCT-x or
SE-CS30-x respectively. Typical values are shown in Table
1. For other systems, refer to the NER Monitor Set-Point
Assistant at www.littelfuse.com/relayscontrols. The Set-
Point Assistant is included with the SE-MON330 software.
2.1.3 V
N
T
RIP
L
EVEL
The SE-330AU uses a DFT algorithm to measure the
fundamental component of neutral voltage (V
N
).
If neutral voltage is greater than the V
N
TRIP LEVEL
setting for the duration of the resistor-fault trip time and
earth-fault current is less than 5% of the CT rating, the
SE-330AU will trip on resistor fault. If the resistor-fault
circuit is tripped and the neutral voltage exceeds the V
N
TRIP LEVEL setting for an interval greater than the EF
TRIP TIME setting, the earth-fault circuit will also trip.
The V
N
TRIP LEVEL range is 20 to 2,000 V with
switch S5 in the 20-k
W
(Vx1) position, and the range is
100 to 10,000 V with switch S5 in the 100-k
W
(Vx5)
position. Calculate the voltage across the NER when
NER current is equal to the pick-up current of the earth-
fault circuit. Set the V
N
TRIP LEVEL at the next largest
value. See Fig. 1 and Section 2.1.4.3.
Typical values are shown in Table 1. For an NER
resistance greater than 2 k
W
, use a 100-k
W
sensing resistor.
For other systems, refer to the NER Monitor Set-Point
Assistant at www.littelfuse.com/relayscontrols.
N
OTE
: A resistor-fault trip is held off if the earth-fault
current is above 5% of the CT rating.
2.1.4 C
ONFIGURATION
S
ETTINGS
Eight configuration switches (S1 to S8) and a
calibration button are located behind the access cover on
the front panel. See Fig. 1.
2.1.4.1 E
ARTH
-F
AULT
-T
RIP
L
ATCH
(S3)
Set switch S3 to select latching or non-latching earth-
fault-circuit operation. See Section 2.4.
2.1.4.2 R
ESISTOR
-F
AULT
-T
RIP
L
ATCH
(S4)
Set switch S4 to select latching or non-latching resistor-
fault-circuit operation. See Section 2.4