NEGATIVE PHASE
SEQUENCE
CURRENT TRANSDUCER
Type CIT300
The Convex Design CIT300 is a sensitive frequency-compensated negative phase sequence (NPS) current transducer for use on 3-phase 50Hz circuits. A 0-12mAdc current output proportional to percentage NPS current is provided such that 12mA is equivalent to 15% NPS current. This output can drive a load of between 10 and 1000 ohms and will not be damaged if the load is open or short circuited.
The nominal input frequency range is 45Hz to 53Hz and can be extended to 40Hz to 55Hz by adjusting the output readings.
The unit is housed in a case suitable for DIN rail mounting or screw fixing inside an equipment cubicle. Input and output connections are made to screw terminals on the front face and all input and output circuits are isolated from earth and from each other to a level of 2KVrms at 50Hz, allowing the summation of two or more outputs.
Power requirements are 48Vdc 1.5W or 110Vdc 2.5W and the nominal input currents are 1A per phase.
Percentage Negative Phase Sequence Current (%NPS Current) is the derived value of current resulting from an imbalance in the three phase currents fed to the transducer, expressed as a percentage of the nominal current.
SPECIFICATION
POWER SUPPLY
CIT300/48 48Vdc (43V to 60V) 1.5W CIT300/110 110Vdc (87.5V to 137.5V) 2.5W
CURRENT INPUTS
Nominal Rating: 1 amp rms Maximum Continuous Current: 3 x nominal Short Term Overcurrent: 10 x nominal for 10 seconds Input Burden: 0.5VA per phase Frequency Range: 40 to 55Hz
OUTPUT
NPS Range: 0-15% of nominal current (0-12mA)
Conversion Ratio: 12mA is equivalent to 15% NPS.
Accuracy
45-53Hz: ±0.1mA (0.125%NPS) with output
loads of between 10 and 1000 ohms.
40-45Hz, 53-55Hz: Increase %NPS reading by 0.075%
NPS per Hz from 45Hz to
40Hz or from 53Hz to 55Hz. e.g.
1) Reading of 15% NPS at 41Hz - actual %NPS is
15+(0.075 x 4) = 15.3% (±0.125%).
2) Reading of 10% NPS at 55Hz - actual %NPS is
10+(0.075 x 2) = 10.15% (±0.125%).
Note: The output will not be damaged if the load is open
or short circuited. Two or more outputs may be
connected together if required.
INSULATION 2KVrms between all input circuits, output circuits
and earth.
Note: The output protection circuitry is connected to earth
via a 2.2nF 6KV capacitor.
ENVIRONMENT EES1980 Class B3.
ELECTRICAL INTERFERENCE EES1980 Class Z.
CASE
Dimensions: W: 150mm H: 73mm D: 114mm.
Weight: 1.2kg.
Terminal face: Polycarbonate/GV/V-0, grey.
Cover: ABS/V-0, grey.
Flame retardancy: Self-extinguishing to UL94 Class V-0
and VDE0304 Degree 1.
Mounting Details:
1) Snap mounting on "top hat" rail.
DIN EN 50 022-35. BS5584.
2) Screw mounting using diagonally-
opposite lugs on rear face.
Terminals: Plus-minus M3.5 terminal screws with self-
lifting connection washer. Torque setting 1Nm.
Convex Design Limited
email:sales@convexdesign.co.uk
Return to
Home Page
Voltage & Current NPS Relays