flux density VPERHZ, internal thermal content in percentage of trip value
THERMSTA. The values are available at local HMI, Substation SAsystem and
PCM600.
10.4.3.4
Setting example
M6496-108 v5
Sufficient information about the overexcitation capability of the protected object(s)
must be available when making the settings. The most complete information is given in
an overexcitation capability diagram as shown in figure
.
The settings
Pickup2
and
Pickup1
are made in per unit of the rated voltage of the
transformer winding at rated frequency.
Set the transformer adapted curve for a transformer with overexcitation characteristics
in according to figure
Pickup1
for the protection is set equal to the permissible continuous overexcitation
= 105%. When the overexcitation is equal to
Pickup1
, tripping
is obtained after a time equal to the setting of t1.
This is the case when
VBase
is equal to the transformer rated voltages.
For other values, the percentage settings need to be adjusted
accordingly.
When the overexcitation is equal to the set value of
Pickup2
, tripping is obtained after
a time equal to the setting of t6. A suitable setting would be
Pickup2
= 140% and t6 =
4 s.
The interval between
Pickup2
and
Pickup1
is automatically divided up in five equal
steps, and the time delays t2 to t5 will be allocated to these values of overexcitation. In
this example, each step will be (140-105) /5 = 7%. The setting of time delays t1 to t6
are listed in table
.
Table 48:
Settings
V/f op (%)
Timer
Time set (s)
105
t1
7200 (max)
112
t2
600
119
t3
60
126
t4
20
133
t5
8
140
t6
4
1MRK 504 163-UUS A
Section 10
Voltage protection
Transformer protection RET670 2.2 ANSI
631
Application manual
Содержание RELION RET670
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