7.3. Measurement Circuits in Three-phase Installations
Voltage measurement
2 voltage transformers in V-connection
Current measurement
Current measurement
Power measurement
Single wattmeter method
use:
equal phase loading, accessible PEN-conductor
result:
total power = 3 × measuring result
Power measurement
Two-wattmeter method
use:
unequal phase loading, non-accessible PEN-conductor;
measuring instruments of the same type have to be used
result:
total power = P1 + P2,
when P1 > P2, the total power = P1 - P2
Power measurement
Two-wattmeter method
2 movements combined into one instrument
Power measurement
Three-wattmeter method
use: unequal phase loading, accessible PEN-conductor
result: total power = P1 + P2 + P3
Power measurement
Three - wattmeter method
3 movements combined into one instrument
Meter circuit (three-wire meter)
Meter circuit (four-wire meter)
Measurement of the power factor (cos φ)
Measurement of the frequency (single frequency meter)
Measurement of the frequency (double frequency meter)
Measurements in a High-voltage Power Plant
