CO M M I SS I O N I N G A N D T E S T I N G G U I D E
19
All current sensors are factory tested for accuracy
in the continues primary current operating range,
i.e., from 5% of rated primary current (4 A) up to
the continues thermal current Icth (4000 A).
These routine tests are made as per the
requirements of the sensor standards IEC
60044-8 or IEC 61869-10.
The test value is 80 A which represents a rated
primary current. Other primary current input
values can be used. However, since sensors are
linear in performance then it is not necessary to
test all primary inputs. If the 80 A primary test
results are within range, then the outputs for the
other primary inputs will be in range.
The chart below shows what the output voltage
should be based on the primary current used.
The acceptable output range is +/- 5.0 % of the
target value shown on the chart.
Multiply the ratio correction factor (ref. Step 1/5
below). This calculated value based on the
correction factors should be /- 0.5% of
the secondary output values shown in the table.
—
Table 1: KECA 80 C184/KECA 80 D85
Primary Current
Input Amps
(60Hz)¹
Secondary
Output (mV)²
KECA 80 C184/
KECA 80 D85
80
180.0
200
450.0
400
900.0
600
1350.0
800
1800.0
1000
2250.0
1200
2700.0
2000
4500.0
3000
6750.0
4000
9000.0
1. Primary injection test equipment assumed to have a +/-0.1%
accuracy or better
2. Output voltage without the use of correction factors to be +/- 5.0%
of secondary output value shown on table above. (e.g., for 80 A
primary, output voltage can be 171 mV to 189 mV). After multiplying
the correction factors to the actual output voltages, the output
voltages should be +/- 0.5% of the values shown in the table. (e.g.,
for 80 A primary, output voltage can be 179.1 to 180.9 mV).
Consideration shall also be given to the accuracy range of the
primary current injection equipment.
3. All values are based on 60Hz.
The test setup to measure the secondary output
of the sensors is shown in Figure 29. ESSAILEC
test socket pt#TC-E-RJ45-INF and RJ45 plug,
pt#FI-RJ45-DIA4 are used to in the illustration
below. These are specifically designed to be used
with ABB digital switchgear with sensors
compliant to the IEC standards.
There may be other similar devices available that
could be used. Measuring device can be any
device capable of measuring the recommended
ranges and comply with the proper IEC standard
input parameters for accurate measuring.
RJ45 connectors have specific pin wiring based
on the requirements of the IEC standards for the
sensors. Test personnel must ensure that any
adapters or connections using RJ45 connectors
meet these requirements.
Extensions of the CAT6 cable can be made up to
about 1 meter in length and must follow the same
pin wiring as the sensor cable.
Supervision
In the protection relay, current metering is
supervised by the CMMXU function. Metering
accuracy is stated in Table 2.
—
Table 2: Current metering accuracy
Characteristic
Value
Operation
accuracy
Depending on the frequency of the
measured current: fn ±2 Hz
±0.5% or ±0.002 × In
(at currents in the range of 0.01...4.00 × In)
A measured value under the zero-point clamping
limit is forced to zero. This allows the noise in the
input signal to be ignored. Read more details in
the technical manual of the protection relay.
