Operation Manual

GMC-I Messtechnik GmbH 9
 Prior to measuring, always set the selector switch for the current
ranges and that for the voltage ranges to the highest range. Make
sure that the set nominal values are never exceeded by more than
1.2 times.
 For power measurements on DC and single-phase AC systems,
set the function switch to the " " position, for power measure-
ments on three-wire, three-phase systems of balanced load to the
" " position.
 To measure the power factor (cos ), set the function switch to
"cos  ind" with inductive load, with capacitive load to "cos  cap".
The connection circuitries for active power and power factor mea-
surements (cos ) are identical and are shown later.
 Switch the meter off after the measurement to avoid unnecessary
load on the batteries (function switch set to position " ").
The symbols used in the equations of the connection circuitries have
the following meaning:
P = Active power in W
Q = Reactive power in var
I = Load current of a phase in A
U = Interlinked generator voltage with three-phase connection in V
cos  = Power factor
a = Readout of the pointer deflection on the corresponding
instrument scale in W, V or A
a  = Readout of the pointer deflection on the cos  scale
c ,c = Scale factor for power measurement
c
I
,
c
U
= Scale constant for current and voltage measurement
ü
I
,
ü
U
= Scale constant for current and voltage measurement