Eaton Industrial Switchgear - Matching of Voltage and Current

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2010 CA08103002Z-EN
15/12 Transformers
Selection and protection of control transformers
Selectionandprotectionofcontrol transformersEngineering
Size selection for control
transformers
Determination of the continuous
rating
The control transformer must be rated
in size so that the voltage drop remains
within the permissible tolerance range
even under unfavorable conditions.
The determination of the transformer
rating is performed by the addition
of all the sealing powers of all
loads which are to be connected
simultaneously as well as addition of
the inrush power of the largest load,
and multiplying the result by a factor
of 0.8.
If the ratings of the loads are very
similar, the sum of all inrush powers of
the simultaneously connected loads is
added to the sum of all the sealing
powers and the result is multiplied by
a factor of 0.8.
Determination of the short-time rating
If the primary requirement is to switch
large contactors, it is recommended
that the control transformer is
selected on the basis of the short-time
rating. In most cases, this will mean
that the transformer rating is reduced.
It is important to ensure that the
sealing power does not exceed the
continuous rating.
Protection of control
transformers
Operational conditions
The protective device shown in the
table below must be connected
upstream of the primary. The overload
release of the circuit-breaker must be
set to the stated current. The current
to be set must also be stated on the
rating plate of the transformer. If a
short-circuit release is present it must
be set to the maximum value.
The setting values of the circuit-
breaker apply up to 1.06 times the
rated voltage. For a higher mains
voltage the +5 % terminal is to be used.
In the case of transformers > 2.0 kVA
(DT...> 4.0 kVA) the circuit-breaker
may trip under certain mains supply
conditions (Ik > 6 kA) and with
unfavorable starting torque. In such
cases we recommend the use of an
inrush current limiter.
The inrush current limiter can be
ordered as an accessory. Ordering
details￫Accessories
ST..., DT...
For all other transformers use transformer-protective circuit-breakers PKZM0-...-T. ￫Page 7/6
Setting range of the motor-protective circuit-breaker as a function of the STI, STZ
and DTZ transformer rated power (VA)
Part no. Primary voltage
200 V 230 V 400 V 415 V 440 V 500 V 690 V
Protective
device
Set-
ting
Protective
device
Set-
ting
Protective
device
Set-
ting
Protective
device
Set-
ting
Protective
device
Set-
ting
Protective
device
Set-
ting
Protective
device
Set-
ting
A A A A A A A
ST…0.06 - PKZM0-0.4 0.3 PKZM0-0.25 0.2 PKZM0-0.25 0.2 PKZM0-0.25 0.2 PKZM0-0.16 0.2 PKZM0-0.16 0.1
ST…0.1 - PKZM0-0.63 0.5 PKZM0-0.4 0.3 PKZM0-0.4 0.3 PKZM0-0.4 0.3 PKZM0-0.25 0.2 PKZM0-0.25 0.2
ST…0.16 - PKZM0-1 0.8 PKZM0-0.63 0.5 PKZM0-0.63 0.5 PKZM0-0.63 0.4 PKZM0-0.4 0.4 PKZM0-0.4 0.3
ST…0.2 - PKZM0-1.6 1.0 PKZM0-0.63 0.6 PKZM0-0.63 0.6 PKZM0-0.63 0.5 PKZM0-0.63 0.5 PKZM0-0.4 0.3
ST…0.25 - PKZM0-1.6 1.3 PKZM0-1 0.7 PKZM0-1 0.7 PKZM0-1 0.7 PKZM0-0.63 0.6 PKZM0-0.63 0.4
ST…0.315 - PKZM0-1.6 1.5 PKZM0-1 0.9 PKZM0-1 0.9 PKZM0-1 0.8 PKZM0-1 0.7 PKZM0-0.63 0.5
ST…0.4 - PKZM0-2.5 2.0 PKZM0-1.6 1.1 PKZM0-1.6 1.1 PKZM0-1.6 1.0 PKZM0-1 0.9 PKZM0-1 0.7
ST…0.5 - PKZM0-2.5 2.4 PKZM0-1.6 1.4 PKZM0-1.6 1.3 PKZM0-1.6 1.2 PKZM0-1.6 1.1 PKZM0-1 0.8
ST…0.63 - PKZM0-4 3.0 PKZM0-2.5 1.7 PKZM0-2.5 1.7 PKZM0-1.6 1.6 PKZM0-1.6 1.4 PKZM0-1.6 1.0
ST…0.8 - PKZM0-4 3.8 PKZM0-2.5 2.2 PKZM0-2.5 2.1 PKZM0-2.5 2.0 PKZM0-2.5 1.7 PKZM0-1.6 1.3
ST…1.0 - PKZM0-6.3 4.7 PKZM0-4 2.7 PKZM0-4 2.6 PKZM0-4 2.5 PKZM0-2.5 2.2 PKZM0-1.6 1.6
ST…1.3 - PKZM0-10 6.3 PKZM0-4 3.5 PKZM0-4 3.4 PKZM0-4 3.2 PKZM0-4 2.8 PKZM0-2.5 2.0
ST…1.6 - PKZM0-10 7.4 PKZM0-6.3 4.2 PKZM0-6.3 4.1 PKZM0-4 4.0 PKZM0-4 3.4 PKZM0-2.5 2.5
ST…2.0 - PKZM0-16 10.0 PKZM0-6.3 5.3 PKZM0-6.3 5.1 PKZM0-6.3 4.8 PKZM0-6.3 4.2 PKZM0-4 3.1
ST…2.5 - PKZ2/ZM-16 11.5 PKZ2/ZM-10 6.6 PKZ2/ZM-10 6.4 PKZ2/ZM-10 6.0 PKZ2/ZM-6 5.3 PKZ2/ZM-4 4.0
ST…3.0 - PKZ2/ZM-25 16.0 PKZ2/ZM-16 10.0 PKZ2/ZM-16 10.0 PKZ2/ZM-10 7.1 PKZ2/ZM-10 6.2 PKZ2/ZM-6 4.5
ST…4.0 - PKZ2/ZM-25 18.1 PKZ2/ZM-16 10.4 PKZ2/ZM-16 10.0 PKZ2/ZM-10 10.0 PKZ2/ZM-10 8.3 PKZ2/ZM-6 6.0
DT…0.1 PKZM0-0.4 0.4 PKZM0-0.4 0.3 PKZM0-0.25 0.2 PKZM0-0.25 0.2 PKZM0-0.25 0.2 PKZM0-0.16 0.1 PKZM0-0.16 0.1
DT…0.16 PKZM0-0.63 0.5 PKZM0-0.63 0.5 PKZM0-0.4 0.3 PKZM0-0.4 0.3 PKZM0-0.4 0.3 PKZM0-0.25 0.2 PKZM0-0.25 0.2
DT…0.25 PKZM0-1 0.8 PKZM0-1 0.7 PKZM0-0.63 0.4 PKZM0-0.63 0.4 PKZM0-0.4 0.4 PKZM0-0.4 0.3 PKZM0-0.4 0.3
DT…0.4 PKZM0-1.6 1.3 PKZM0-1.6 1.1 PKZM0-1 0.7 PKZM0-1 0.6 PKZM0-0.63 0.6 PKZM0-0.63 0.5 PKZM0-0.63 0.4
DT…0.5 PKZM0-2.5 1.6 PKZM0-1.6 1.4 PKZM0-1 0.8 PKZM0-1 0.8 PKZM0-1 0.7 PKZM0-1 0.6 PKZM0-0.63 0.5
DT…0.63 PKZM0-2.5 2.0 PKZM0-2.5 1.8 PKZM0-1.6 1.0 PKZM0-1.6 1.0 PKZM0-1 0.9 PKZM0-1 0.8 PKZM0-0.63 0.6
DT…1.0 PKZM0-4 3.1 PKZM0-4 2.7 PKZM0-2.5 1.6 PKZM0-1.6 1.5 PKZM0-1.6 1.4 PKZM0-1.6 1.3 PKZM0-1 0.9
DT…1.6 PKZM0-6.3 5.0 PKZM0-6.3 4.3 PKZM0-4 2.5 PKZM0-2.5 2.4 PKZM0-2.5 2.3 PKZM0-2.5 2.0 PKZM0-1.6 1.4
DT…2.0 PKZM0-6.3 6.2 PKZM0-6.3 5.4 PKZM0-4 3.1 PKZM0-4 3.0 PKZM0-4 2.8 PKZM0-2.5 2.5 PKZM0-2.5 1.8
DT…2.5 PKZM0-10 7.6 PKZM0-10 6.7 PKZM0-4 3.8 PKZM0-4 3.7 PKZM0-4 3.5 PKZM0-4 3.1 PKZM0-2.5 2.2
DT…4.0 PKZM0-16 12.0 PKZM0-16 10.4 PKZM0-6.3 6.0 PKZM0-6.3 5.8 PKZM0-6.3 5.5 PKZM0-6.3 4.8 PKZM0-4 3.5
DT…6.3 PKZ2/ZM-25 18.9 PKZ2/ZM-25 16.4 PKZ2/ZM-10 9.5 PKZ2/ZM-10 9.1 PKZ2/ZM-10 8.6 PKZ2/ZM-10 7.6 PKZM0-6.3 5.5