16
UMG 103
c
B
A
L3
N
L1
L2
Voltage measurement
The UMG103 is designed for operation
in low-voltage distribution systems, in
which overvoltage category III (300 V)
impulse voltages can occur.
The UMG103 can measure L-N voltages of
up to 240 V and short-term overvoltages
up to 300 Vrms.
The UMG103 can be used in three-phase 4
conductor system (TN, TT system) (50 Hz,
60 Hz) with earthed PEN conductor.
The UMG103 draws the power supply
voltage required for operation from the
measuring-circuit voltage.
The instrument leads required for the
voltage measurement must be suitable
for voltages up to 300 VAC to earth and
520 VAC conductor to conductor.
Instrument leads must be fused by an
overcurrent protective device and routed
via disconnectors.
The UMG103 is only conditionally
suitable for measurements in medium
and high-voltage distribution systems,
as it draws the power supply voltage
from the measuring-circuit voltage and
therefore loads the voltage transformer
with a non-linear current.
Fig.16.1 Connection example: Voltage
measurement via disconnectors and
fuses.
Disconnector
Fuse (6A type C)
Important!
The voltage measurement inputs
are hazardous live!
