Connection To Medium And High Voltage (Aron Circuit) - Landis+Gyr E650 Series User Manual

Installation and De-Installation
Preliminary fuses
4.1.2

Connection to Medium and High Voltage (Aron Circuit)

Earthing
Three-phase
three-wire meter
D000030110 d – E650 Series 3 (ZMD400AT/CT, ZFD400AT/CT) – User Manual
The preliminary (supply) fuses in the voltage circuit (max. 10 A) protect
against short-circuits in the measuring circuit. The voltage circuits are con-
nected directly to the primary and would only be protected by the main
fuses of 100 A or more if the preliminary fuses were not fitted. A short-cir-
cuit would certainly destroy the measuring device.
This circuit is used above all in the medium voltage range (3 to 30 kV) and
rarely with high voltage (from 30 kV).
It is also recommended here to insert a test terminal block between trans-
former and measuring device (meters and others). This permits simple ex-
change without interrupting operation. On the other hand, no preliminary
supply fuses are necessary in the voltage circuits, since the voltage trans-
formers cannot produce a high short-circuit capacity on the secondary side.
On medium and high voltage the secondary side of all voltage transformers
should be earthed for safety reasons. Otherwise potentials could develop,
which could result in dangerous contact voltages.
Fig. 4.2 Connection to medium and high voltage (Aron circuit)
Instead of the three-phase three-wire meter ZFD400 the power supply
company can also use a three-phase four-wire meter ZMD400. The
following two connections are then possible:

with 2 voltage transformers and open star point at the meter

with 3 voltage transformers and star point connected at the meter
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