Siemens 3RK1308‑0 00‑0CP0 Series Equipment Manual page 55

Variant 2. High Feature DOL starter or reversing starter with 230 V brake
The current for the braking device is drawn from only one switched phase. Connection is via
T1.
The single-phase connection of the motor brake leads to phase asymmetry at the motor
connection. This is detected by the motor starter, which responds based on its parameter
settings and the magnitude of the asymmetry.
Asymmetry limit:
The asymmetry limit is a percentage value by which the motor current is allowed to deviate
in each phase. Asymmetry is detected as soon as one of the three phases deviates by more
than 40 % from the mean value of all phases.
Response to asymmetry:
You use this device parameter to determine the behavior of the motor starter in the event of
asymmetry:
● Warning (not permissible for fail-safe motor starters in ATEX operation)
● Shutdown
Note
Using brake motors
When using brake motors, you have to increase the set rated motor current by the braking
current (see example on motor and brake starting current later in this chapter).
NOTICE
Using this mode
This operating mode is not suitable for 3RK1308-0C and 3RK1308-0D fail-safe
motor starters as there is a connection to the neutral conductor.
Motor starter (3RK1308‑0**00‑0CP0)
Equipment Manual, 11/2019, A5E34821005002A/RS-AC/003
Product features
5.8 Operating motor starters
55