Atec CTER91 User Manual
CTER-91
Current Transformer Excitation,
Ratio and Polarity Test Set
■
Can test bushing CTs mounted inside
transformer or switchgear
■
Saturation, ratio and polarity tests
performed without changing test lead
connections
■
Overload and short-circuit protection
CTER-91
Current Transformer Excitation, Ratio and Polarity Test Set
DESCRIPTION
The CTER-91 test set is a lightweight, portable unit for
performing excitation, ratio and polarity tests on current
transformers using the voltage-comparison method.
Utilizing the latest technology, Model CTER-91 provides a
variable voltage output and precision instrumentation for
testing single and multiratio CTs. All three tests –
excitation, ratio and polarity – can be performed without
changing any leads.
Current transformers can be tested in their equipment
configuration, such as being mounted in transformers, oil
circuit breakers or switchgear.
It is necessary for the equipment to be totally isolated
from the electrical system prior to testing.
APPLICATIONS
Saturation Test
Model CTER-91 provides a variable voltage output and
digital instrumentation for measuring the excitation voltage
and excitation current that results as the voltage applied to
the CT under test is increased.
As the CT under test begins to saturate, a large increase in
current will be detected for a small increase in voltage.
Ratio Test
The ratio test is performed by comparing a voltage applied
to the secondary winding to the resulting voltage
produced on the primary winding.
For example, if 1 volt per turn is applied to the secondary
winding, the voltage present on the primary winding
would be 1 volt.
More specifically, if 120 volts were applied to the
secondary of a 600/5 current transformer (120:1 ratio), 1
volt would be present on the primary winding.
Polarity Test
Polarity of the current transformer under test is determined
by special circuitry that divides the voltage applied to the
secondary winding by either 10 or 100, depending on
switch position, then adds the result to the primary
voltage.
An increase in magnitude indicates correct polarity, and a
decrease shows incorrect polarity.
FEATURES AND BENEFITS
■
Voltmeter can be used to measure external voltages up
to 600 volts ac.
■
A RUN/HOLD switch freezes readings on instruments
when switched to the HOLD position.
■
A low range of 40 volts is provided for CTs that saturate
at low voltages.
■
The unit provides a high range of 1000 volts.
■
A zero-start interlock is incorporated. This minimizes the
possibility of energizing the CT under test with a sudden
high voltage.
CTER-91
Current Transformer Excitation, Ratio and Polarity Test Set
SPECIFICATIONS
Input
120 V, 1f, 50/60 Hz OR 240 V, 1f, 50/60 Hz
Output
Continuously variable in four ranges:
0 to 40 V at 1.5 A max
0 to 150 V at 1.5 A max
0 to 600 V at 1.5 A max
0 to 1000 V at 1.0 A max (5 min on, 15 min off)
Instrumentation
Voltmeters
Two 4
1
⁄
2
-digit, autoranging
Solid-state Instruments
Ranges: 0.0000 to 1.9999/19.999/199.99/600.0/1000 V
Accuracy: ±0.25% of reading, ±1 digit for 1 to 1000 V; ±1% of
reading ±1 digit for 0.2 to 1 V
Ammeter
One 4
1
⁄
2
-digit
Solid-state Instrument
Range: 0.0000 to 1.9999 A
Accuracy: ±0.85% of reading, ±1 digit
Enclosure
The unit is housed in a high-strength, molded suitcase-type
enclosure with carrying handle and removable cover.
Storage space is provided for test leads.
Dimensions
9.9 H x 14.1 W x 11.9 D in.
(251 H x 357 W x 287 D mm)
Weight
37 lb (16.8 kg)
Connections for verifying ratios of a multiratio CT
Connections for performing saturation, ratio and polarity tests
Item (Qty) Cat. No.
Model CTER-91
115 volt input, 50/60 Hz CTER-91-115
230 volt input, 50/60 Hz CTER-91-230
Included Accessories
Test leads
18 AWG, 5 ft (1.5 m) [1 pr] 1282
18 AWG, 12 ft (3.7 m) [1 pr] 2997
Line cord [1] 6828
Instruction manual [1] 14355
ORDERING INFORMATION
UK
Archcliffe Road Dover
CT17 9EN England
T +44 (0) 1304 502101
F +44 (0) 1304 207342
UNITED STATES
4271 Bronze Way
Dallas TX75237-1088 USA
T 800 723 2861 (USA only)
T +1 214 330 3203
F +1 214 337 3038
OTHER TECHNICAL SALES OFFICES
Valley Forge USA, Toronto CANADA,
Mumbai INDIA, Trappes FRANCE,
Sydney AUSTRALIA, Madrid SPAIN
and the Kingdom of BAHRAIN.
Registered to ISO 9001:2000 Reg no. Q 09290
Registered to ISO 14001 Reg no. EMS 61597
CTER_91_DS_en_V10
www.megger.com
Megger is a registered trademark
BUSHING CT'S
SEC + 10 – PRI
VOLTAGE RANGE
150
40
SEC + 10 + PRI
CB2
SATURATE AND
HOLD
RATIO TEST
RUN
600
1000
OFF
ON
OFF
H1
H2
PRIMARY EXTERNAL VOLTS
X1
X2
X1-X
5
V
SECONDARY VOLTS
E
O
X
L
T
T
S
A
E
M
X
P
T
S
AMPERES
SEC + 10 – PRI
VOLTAGE RANGE
150
40
SEC + 10 + PRI
CB2
SATURATE AND
HOLD
RATIO TEST
RUN
600
1000
OFF
ON
OFF
H1
X5
X4
X3
X2
X1
H2
X1
X2
V
E
O
X
L
T
T
S
A
E
M
X
P
T
S
PRIMARY EXTERNAL VOLTS
SECONDARY VOLTS
AMPERES
TEST SELECTOR
SEC + 100 + PRI
SEC + 100 – PRI
EXT METER
CONNECTION
VERNIER OUTPUT
OUTPUT
TEST SELECTOR
SEC + 100 + PRI
SEC + 100 – PRI
EXT METER
CONNECTION
VERNIER OUTPUT
OUTPUT
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