ABB Relion REG670, Applications Manual

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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.
10.4.3.3 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.
10.4.3.4 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
209 .
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
209 .
V/Hz> for the protection is set equal to the permissible continuous overexcitation
according to figure 209 = 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
47 .
1MRK 502 071-UEN -
Section 10
Voltage protection
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 423
Application manual