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Electro Industries/GaugeTech
Doc # E107706 V1.25 7-6
Q
Meter/Installation Data
Enter the Numerator and Denominator for each instrument transformer. For example, a PT with a ratio
of 7200/120 has a numerator or 7200, a denominator or 120 and a multiplier of 60 ( 7200/120 = 60/1).
Q
Base Conversion Factors
For Transformer Voltage, enter the Phase-to-Neutral value of Test Voltage previously calculated. For
Transformer Current, enter the Full-Load Current previously calculated. For Multipliers, enter the PT
and CT multipliers previously calculated.
TrfIT Secondary is the Base Value of Voltage and Current at the Instrument Transformer Secondary of
the Power Transformer. These numbers are obtained by dividing the Transformer Voltage and Current
by their respective Multipliers. The Meter/Trf values for Voltage and Current are obtained by dividing
the Meter Base values by the TrfIT Secondary values.
Q
Load Loss at Transformer
No-Load Loss Watts (kW) = 1-Phase kW No-Load Loss = ______________
No-Load Loss VA (kVA) = (%Exciting Current) * (1-Phase kVA Self-Cooled Rating) / 100
= (______________) * (________________) / 100
= _______________ kVA
No-Load Loss VAR (kVAR) = SQRT((No-Load Loss kVA)
2
- (No-Load Loss kW)
2
)
= SQRT((_________________)
2
- (________________)
2
)
= SQRT((__________________) - (_________________))
= SQRT (_________________)
= ____________________
Instrument Transformers Numerator Denominator Multiplier
Potential Transformer
Current Transformer
Power Multiplier [(PT Multiplier) times (CT Multiplier)]
Meter Secondary Voltage (volts) 120
Meter Secondary Current (amps) 5
Quantity
Voltage
Current
Transformer Multiplier Trf IT Sec Meter Base Meter/Trf
120
5