ABB RED615 Technical Manual page 257

1YHT530004D05 D
615 series
Technical Manual
and are set through the Time constant start, Time constant normal and Time
constant stop settings. Only one time constant is valid at a time.
Table 257: 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 IED 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 IED 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 startup condition of a motor and at the
end of the startup 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 startup 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
startup, 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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