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Emax X1-Tmax T7-Tmax T8
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Doc N°
Mod.
Apparatus
Scale
Page No
1SDH000587R0002
3.10.1.3. Voltage transformer
In the case of three-phase systems with a rated voltage greater than 690 Vrms phase to phase or with a PR330/V module con-
nected by external sockets, a step-down transformer (with a transformation ratio of less than 1).
Proper operation is only guaranteed for star/star or delta/delta configurations.
The allowable primary and secondary rated voltages that must be set on the unit are specified.
Standard single transformers:
Mechanical characteristics
Fixture
DIN rail EN 50022
Material
self-extinguishing thermoplastic
Degree of protection
IP30
Electrostatic protection
shielded towards EARTH
Electrical characteristics
Precision class
cl. 0,5
Performance
≥
10VA...
≤
20 VA
Overload
20% permanent
Insulation
4 kV between inputs and outputs
4 kV between inputs and outputs
4 kV between inputs and inputs
Operating frequency range
from 50 Hz to 60 Hz, ± 10%
The following is a summary table of standard VT connections according to the type of plant.
The VTs must have a performance coming between the values of 10 and 20VA inclusive, 4 kV insulation between the primary
and secondary.
Installation system
"VT Standard" type transformer
(Star/Star)
"VT Standard" type transformer
(Delta/Delta)
Application diagram
Application diagram
TN-C
B
A
TN-S
B
A
IT with neutral
B
A
IT
n.c
A
TT with neutral
A
B
TT without neutral
n.c
A
Note for B diagram:
- for TN-C systems the connection must be made to PEN
- for TN-S systems the connection must be made to N for configurations with neutral or PE for configurations without neutral; if
the PE is used, the current thereon could be around a dozen mA. If a customer considers this value too high or has a residual
current protection which risks being tripped, then application diagram A must be used.
- for IT and TT systems with neutral, the connection must be made to N.
Application diagram B
Application diagram A
N
WARNING: The maximum length of the VT - PR330/V wiring must not exceed 15 meters.
Use corded shielded two-wire cable (e.g. BELDEN 3105A two-wire cable).
The shield must be connected to earth on both sides.
WARNING: Dielectric strength tests must not be performed on the inputs and outputs of the protection release
and on the secondary lines of any VT connected.
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