ABB RELION REX640, Техническое руководство, Страница: 432 / 1960

and long-time thermal history, allowing more critical situations like motor start-ups
to be taken into consideration more carefully.
Setting of thermal restart level
The
Restart thermal Val can be calculated as follows:
= 100% −
− ℎ
ℎ
∙ 100% +
(
)
(Equation 55)
For instance, if the start-up time of the motor is 4 seconds, and the calculated
operate time of the thermal protection stage for cold motor is 6 seconds, one
motor start-up will use 4/6 = 66.6% of the thermal capacity of the motor. Therefore,
the
Restart thermal Val must be set to below 100% - 66.6% = 33.3% say to 28.3%
(100% - (66.6% + margin), where margin is 5%).
Setting of thermal alarm level
Tripping due to high overload can be avoided by reducing the load of the motor
when the thermal level reaches a set alarm level.
The
Alarm thermal value can be set to a level, which will allow the use of the motor’s
full thermal capacity without causing a trip due to long time overload. Generally, the
Alarm thermal value is set to 80….90% of the trip level.
4.1.11.7 Signals
RPTTR Input signals
Table 488: RPTTR Input signals
Name Type Default Description
I3P SIGNAL - Three-phase currents
U3P SIGNAL - Three-phase voltages
BLOCK BOOLEAN 0=False Block signal for acti-
vating the blocking
mode
START_EMERG BOOLEAN 0=False Signal for indicating
the need for emer-
gency start
AMB_TEMP FLOAT32 0 The ambient temper-
ature used in the cal-
culation
Protection functions 1MRS759142 F
432 REX640
Technical Manual