Service Value Report; Setting Example - ABB RET650 Applications Manual

Section 8
Voltage protection
8.4.3.3
8.4.3.4
160
tMax: For overvoltages close to the set value times can be extremely long if a high
K time constant is used. A maximum time can then be set to cut the longest times.
Typical settings are 1800-3600 seconds (30-60 minutes)
AlarmLevel: Setting of the alarm level in percentage of the set trip level. The alarm
level is normally set at around 98% of the trip level.
tAlarm: Setting of the time to alarm is given from when the alarm level has been
reached. Typical setting is 5 seconds.

Service value report

A number of internal parameters are available as service values for use at
commissioning and during service. Remaining time to trip (in seconds)
TMTOTRIP, flux density VPERHZ, internal thermal content in percentage of trip
value THERMSTA. The values are available at local HMI, Substation SAsystem
and PCM600.

Setting example

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 62.
The settings V/Hz>> and V/Hz> 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 62.
V/Hz> for the protection is set equal to the permissible continuous overexcitation
according to figure 62 = 105%. When the overexcitation is equal to V/Hz>,
tripping is obtained after a time equal to the setting of t1.
This is the case when UBase 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 V/Hz>>, tripping is obtained
after a time equal to the setting of t6. A suitable setting would be V/Hz>> = 140%
and t6 = 4 s.
The interval between V/Hz>> and V/Hz> 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 19.
1MRK 504 169-UEN A
Transformer protection RET650 2.2 IEC
Application manual
M6496-144 v4
M6496-108 v5