Voltage Transformer - ABB Tmax T7 Operating Instructions Manual

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
Material
Degree of protection
Electrostatic protection
Electrical characteristics
Precision class
Performance
Overload
Insulation
Operating frequency range
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
TN-C
TN-S
IT with neutral
IT
TT with neutral
TT without neutral
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 A
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.
B0431
Mod.
DIN rail EN 50022
self-extinguishing thermoplastic
IP30
shielded towards EARTH
cl. 0,5
≥10VA...≤20 VA
20% permanent
4 kV between inputs and outputs
4 kV between inputs and outputs
4 kV between inputs and inputs
from 50 Hz to 60 Hz, ± 10%
"VT Standard" type transformer
(Star/Star)
Application diagram
B
B
B
n.c
A
n.c
B1751
"VT Standard" type transformer
Application diagram
Application diagram B
N
Apparatus
Emax X1-Tmax T7-Tmax T8
1SDH000587R0002
Doc N°
(Delta/Delta)
A
A
A
A
B
A
Scale
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