Signals - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.1.9.7
400
Setting the thermal restart level
The restart disable level can be calculated as follows:

startup time of the motor
θ
100 %

= −
i

operate time when no prior load

GUID-0ECFC5C4-0982-4BA7-B481-63A4131718FF V1 EN
For example, the motor start-up time is 11 seconds, start-up current 6 x rated and Time
constant start is set for 800 seconds. Using the trip curve with no prior load, the
operation time at 6 x rated current is 25 seconds, one motor start-up uses 11/25 ≈ 45
percent of the thermal capacity of the motor. Therefore, the restart disable level must
be set to below 100 percent - 45 percent = 55 percent, for example to 50 percent (100
percent - (45 percent + margin), where margin is 5 percent).
Setting the thermal alarm level
Tripping due to high overload is avoided by reducing the load of the motor on a prior
alarm.
The value of Alarm thermal value is set to a level which allows the use of the full
thermal capacity of the motor without causing a trip due to a long overload time.
Generally, the prior alarm level is set to a value of 80 to 90 percent of the trip level.

Signals

Table 443: MPTTR Input signals
Name Type
I3P SIGNAL
BLOCK BOOLEAN
START_EMERG BOOLEAN
AMB_TEMP FLOAT32
Table 444: MPTTR Output signals
Name Type
OPERATE BOOLEAN
ALARM BOOLEAN
BLK_RESTART BOOLEAN
TEMP_RL FLOAT32

10 0 0 % + margin

⋅


Default Description
- Three-phase currents
0=False Block signal for activating the blocking mode
0=False Signal for indicating the need for emergency start
0 The ambient temperature used in the calculation
Description
Operate
Thermal Alarm
Thermal overload indicator, to inhibit restart
Analog output
1MRS759142 C
(Equation 43)
REX640
Technical Manual