Wiring Power Meters
Ben Kemink
Subjects covered:
to re-wire an incorrect NEGATIVE average power situation.
to connect Single-Phase, Two-Phase , Three-Phase- Three-Three-Wire and Three-Phase-Four-Wire loads.
to connect safely measurement transformers between the loads and power meters.
more about the magic of the virtual ground box
Why ring?
i
u
Source Wiring Load
Make a drawing
Positive “DC”
+ -
I
U
Negative “DC”
-
+ U
I
Always: First Connect the Current !
i
u i
v +
-
Wiring Sequence
Correct Connection
The sign of the current is positive, when the current flows from [I]
terminal to [±] terminal inside the powermeter shunt.
The sign of the voltage is positive when the voltage of the [V]
terminal is higher than [±] terminal.
I
V
i
v
+ -
I
V i
v
+
-
v i p
Pavg
v i
p
Pavg
The voltage source increases and the current also
Incorrect Voltmeter connection
v i
p
Pactive
The power meter displays negative value for average power.
I
V i
v
+
-
The source voltage decreases but the current increases.
Incorrect Current meter connection
v
i
p
Pactive
I
V i
v
+
-
Connect CURRENT METER if possible in RETURN WIRE
Return wire is at lower voltage than “HOT” wire, after the voltage drop in the load.
Wiring Single-Phase Three-Wire
Wiring Three-Phase Four-Wire
Wiring Three-Phase Three-Wire
Wiring Yokogawa Three-Voltage Three-Current
The Only Correct Way to Measure the Phase Voltage!
THREE PHASE SYSTEMS Artificial Neutral
