24 | Installation
Power Quality Controller – PQC | Operating Manual | FRAKO
5.2.7 Current measurement
The PQC is designed for connection to x/1 A and x/5 A external current transform-
ers electrically isolated from the power supply. Depending on the instrument type,
the PQC can measure one, two or three AC currents. Attention must be paid to the
allowable measurement range. See
for further information.
WARNING!
Danger from electricity!
If live current transformer circuits are interrupted, there is the danger that
arcing may occur, which could cause electric shock, burns or eye injuries.
In addition, red-hot metal particles could be spattered, which apart from
the health hazard also constitute a fire risk.
– The retaining screws on the connectors must be tightened to prevent the
connectors accidently working loose.
– The secondary-side connections of the current transformers must be
short-circuited before the circuits to the PQC are interrupted or the con-
nector removed!
Note
If an earth terminal is provided at the secondary side of the current trans-
former, this must be connected to an earthing conductor! We recommend
in general that every current transformer circuit be earthed.
Instrument types with single-phase measurement:
The current can be measured in any desired phase, with the current transformer cir-
cuit connected to the
L
terminals
S1
and
S2
as shown in the diagram (see
5.2.10.1 “Connection diagram: Type PQC 1202401-xx”
).
Instrument types with 3-phase measurement:
The current transformer circuits must be connected to the respective S1 and S2 ter-
minals for each of the phases L1, L2 and L3, as shown in the diagram (see
5.2.10.2 “Connection diagram: Type PQC 1202403-xx”
).
Unassigned current measurement inputs can be left unconnected.
Note
In networks with a nominal voltage of 1000 V and more, the regulations call
for the current transformer circuits to be earthed.
If networks with a nominal voltage of 1000 V or over are left unearthed,
damage may occur to the instrument.
With three-phase measurement, automatic connection identification is not
possible.