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2 Functions

7UT613/63x Manual

C53000-G1176-C160-2

Figure 2-1 Transformer bank, consisting of 3 single-phase auto-transformers with current

comparison via each single phase

• Such current comparison is more sensitive to 1-phase earth faults in one of the

transformers than the normal differential protection. This has a certain importance

considering that 1-phase earth faults are the most probable faults in such banks.

• On the other hand, the compensation winding cannot and must not be included into

this protection even if it is accessible and equipped with current transformers. This

application variant is based on the current law in that all currents flowing into a

winding must total to zero.

• If this protection variant is desired, set address 105 to PROT. OBJECT = Autotr.

node.

• Equal setting is valid for generators

and motors. The setting PROT. OBJECT =

Generator/Motor also applies to series reactors

and shunt reactors, if a com-

plete 3-phase set of current transformers is connected to both sides.

• For the operation of mini-busbars

set PROT. OBJECT = 3ph Busbar. The

maximum number of feeders is determined by the number of three-phase measure-

ment inputs of the device. 7UT613 and 7UT633 allow a maximum number of 3,

7UT635 a maximum of 5 measuring locations. This setting applies also to short

lines which are terminated by two sets of current transformers. „Short “ means that

the current transformer connections from the CTs to the device cause no impermis-

sible burden for the current transformers.

• If the device is used as busbar

as 1-phase device or via summation transformer as

3-phase device, the setting PROT. OBJECT = 1ph Busbar applies. The maximum

number of feeders is determined by the number of single-phase measurement

inputs of the device (7UT613 and 7UT633 provide up to 9, 7UT635 up to 12 mea-

surement inputs).

Differential Protec-

tion

The differential protection is the main protective function of the device. Address 112

DIFF. PROT. is thus set to Enabled.

Siemens SIPROTEC 7UT63 series User Manual

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