Installation
Operating Manual EM-PQ 2300
17
DANGER!
Live current transformer circuits must never be interrupted. There is a danger that arcing may
occur, which could cause burns or electric shock.
The secondary-side connections of the current transformers must be short-circuited at the
transformers before the circuits to the EM-PQ 2300 are interrupted!
Exceptions: If the current transformers in use are equipped with internal open circuit protectors in
good working order in the secondary circuits, or if a test switch that automatically short-circuits the
current transformer secondary side is fitted. In the latter case, it is essential that the correct
functioning of the short-circuiting switch has been verified before it is then left in the
‘Test’ position
for any work on the circuit.
Note: Modern current transformers installed in power systems are, as a rule, equipped with an
internal open circuit protector, which acts to protect the secondary circuit upon this being opened.
However, it is absolutely essential that the presence of an open circuit protector in good working
order be verified before a current transformer secondary circuit is opened.
A safe procedure is to short-circuit the secondary side on the current transformer side of the
terminals to be opened.
DANGER!
Live current transformer circuits must never be interrupted. There is a danger that arcing may
occur, which could cause burns or electric shock.
The retaining screws on the sides of the connectors for the current transformer circuits must
always be tightened before the instrument is put into service.
Tightening these retaining screws prevents the connectors from accidentally working loose and
therefore reduces the risk of arcing.
DANGER!
If an earth terminal is provided at the secondary side of the current transformer, this must be
connected to an earthing conductor!
CAUTION!
The following must be observed to ensure safe and reliable operation:
The connection of the current measurement inputs must be via an external, electrically
isolating current transformer.
Overloading of the current transformers incorporated in the instrument must be avoided.
The maximum allowable continuous current is 6 A AC; transient peaks 10 A.
These measures must be taken to ensure that the instrument is not damaged.
The EM-PQ 2300 can measure five AC currents, whose respective inputs are electrically isolated from each
other. See
Section 2, Technical data, page 7
for the measurement ranges.
The currents in the phases L1, L2 and L3, plus those in the neutral conductor N and the protective earth
conductor PE, are measured via external current transformers. Instead of the protective earth another conductor
can also be connected, provided that its parameters are within the range specified in
Section 2, Technical data,
page 7
.
The terminals
L1
– S1-S2
,
L2
– S1-S2,
L3
– S1-S2,
N
–S1-S2
and
Lx
– S1-S2
must be connected as shown in the connection
diagram Fig. 5 on page 14. This shows the 3-phase connections with the
additional measurements in the N and PE conductors.
Unassigned current measurement inputs can be left unconnected.
