Iso-Tech IPM 138 Instruction Manual page 16

Underrange display :
0.000 kW : Vrms <0.5V or Arms <0.5A
PF - - - - : Vrms <0.5V or Arms <0.5A
Overrange display:
OL.U : Voltage overload ( Vrms > 1000V)
OL.A : Current overload (Arms > 620A)
OL.UA : Both Voltage and current overload.
±OL kW : Active Power > 600 kW or < -600 kW.
3-2 Three Phase Power Measurement
a. 3-phase 3 wire balanced / unbalanced
Set the rotary switch to the PF W~ position.
W=W1+W2
1
3
2
Wye or star
Black
W1
W2
Red
Black
Red
EN-16