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MF790c TEST REQUIREMENT
For ENERGY METERING
MF790c Test Requirement – Energy Metering
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MF790c ENERGY METERING TEST REQUIREMENT
MF790c is a protective relay, its energizing inputs are fed from Electronic current and
Electronic voltage transformers connected to the power circuit. It is an alternative for
conventional type (CT PT with Relay) protection and metering application.
Since its energizing inputs (Electronic current transformer- ECT and Electronic voltage
transformers EVT secondary values) are different from the conventional CT & PT operated
Relays, to perform accuracy tests on MF790c for Metering functions we generally use the following
test connection set up and procedure.
Tests to be conducted
1.
Determination of Accuracy of Energy (KWh and KVArh) measurements and comparison
with conventional type reference meter. Test points and accuracy limits are chosen from
XXXXX.
We would like to know the feasibility of doing the test with same arrangements at your lab and get
certified. We also intend to discuss if any other better alternatives is suggested from your end.
MF790c Test Requirement – Energy Metering
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TEST SET UP / CONNECTION DIAGRAM
MF790c Test Requirement – Energy Metering
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Device details/Specification
Ref in Diagram
Device
Specification
MTJ-1, MTJ-2, MTJ-3
Multi turn test jigs
No of turns = 50
VT1
Voltage transformer 1
VT2
Voltage transformer 2
CT-R, CT-Y, CT-B
Current transformers
VS-R, VS-Y, VS-B
EVT / Voltage Sensors
11000/√3V : 2/√3V Class 0.2
CS-R, CS-Y, CS-B
ECT / Current Sensors
250/150 mV, Class 0.2
MF790c
Numerical Relay
Refer Technical spec
RM
Reference meter
(for comparison)
Scope of Test laboratory
11000/√3V : 110/√3V, Class 0.2
11000/√3V : 110/√3V, Class 0.2
250/1 A, class 0.2
Procedure:
1.
As per test requirement Test voltage shall be applied on low voltage winding of 3 Phase
voltage transformer 1 from accurate test source and developed voltage on its HV winding is
made sensed by primary of EVT and voltage transformer 2 then its secondary outputs from
EVT and voltage transformer 2 are fed to MF790c and reference meter’s Voltage
Energizing inputs respectively.
2.
As per test requirement Test current from accurate test source shall be applied to multiple
wire turns made on primary of ECTs and Current transformers to get high current
equivalent. Then its secondary outputs from ECTs and current transformers are fed to
MF790c and reference meter’s current Energizing inputs respectively.
3.
The magnitude and phase angle of voltage and currents can be varied according to our test
requirement. And test results shall be recorded.
MF790c Test Requirement – Energy Metering