ABB RELION 611 Series Technical Manual page 155

1MRS757454 D
611 series
Technical Manual
Time constant start, Time constant normal and Time constant stop settings. Only one
time constant is valid at a time.
Table 143: Time constant and the respective phase current values
Time constant (tau) in use
Time constant start
Time constant normal
Time constant stop
The Weighting factor p setting determines the ratio of the thermal increase of the two
curves θ and θ .
A B
The thermal level at the power-up of the protection relay is defined by the Initial
thermal Val setting.
The temperature calculation is initiated from the value defined in the Initial thermal
Val setting. This is done if the protection relay is powered up or the function is turned
off and back on or reset through the Clear menu.
The calculated temperature of the protected object relative to the operate level, the
TEMP_RL output, is available through the monitored data view. The activation of the
BLOCK input does not affect the calculated temperature.
The thermal level at the beginning of the start-up condition of a motor and at the end
of the start-up condition is available in the monitored data view at the THERMLEV_ST
and THERMLEV_END outputs respectively. The activation of the BLOCK input does
not have any effect on these outputs.
Alarm and tripping logic
The module generates alarm, restart inhibit and tripping signals.
When the thermal level exceeds the set value of the Alarm thermal value setting, the
ALARM output is activated. Sometimes a condition arises when it becomes necessary
to inhibit the restarting of a motor, for example in case of some extreme starting
condition like long starting time. If the thermal content exceeds the set value of the
Restart thermal val setting, the BLK_RESTART output is activated. The time for the
next possible motor start-up is available through the monitored data view from the
T_ENARESTART output. The T_ENARESTART output estimates the time for the
BLK_RESTART deactivation considering as if the motor is stopped.
When the emergency start signal START_EMERG is set high, the thermal level is set
to a value below the thermal restart inhibit level. This allows at least one motor start-
up, even though the thermal level has exceeded the restart inhibit level.
Protection functions
Phase current
Any current whose value is over 2.5 x I
Any current whose value is over 0.12 x I
currents are below 2.5 x I
r
All the currents whose values are below 0.12 x I
Section 4
r
and all
r
r
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