4 Short-circuit / motor protection
4.2 Motor protection
28 EMS2… Electronic motor starter 10/19 MN034003EN www.eaton.com
4.2.1 Symmetry detection
The motor currents are measured at phases L1 and L3 and monitored for
symmetry.
If the motor currents deviate by more than ≥ 33 %, the motor shuts down
within 2 minutes.
If the motor currents deviate by more than ≥ 67 %, (e.g., phase failure),
the motor shuts down within 2 seconds.
The deviation can be calculated using the following formulas.
|I
max
| > I
nenn
→ deviation = (I
max
- I
min
)/I
max
|I
max
| < I
nenn
→ deviation = (I
max
- I
min
)/I
nenn
4.2.2 Motor with brake
If a motor with brake (connection in the motor terminal board) is connected,
the 400 V AC brake must be linked to the 2/T1 and 6/T3 terminals.
A 230 V AC brake must be connected to the 4/T2 terminals and the star point
of the motor.
WARNING
Below the minimum device current, the motor on the EMS2
motor starter is ineffective.
￫
The setting for the motor protection can only be changed in
parameterization mode.
The position of the potentiometer on the front of the EMS2 is
not an indicator of the actual set value.
In the delivery state, it is set to the lowest value.
See also ￫ section 4.2.3, “Conditions when setting the motor
protection”, page 29.
￫
In the event of high clock rates, the motor protection function
may trip due to the increased switch-on currents
WARNING
Increase motor current monitoring to the nominal brake current.
This should be set accordingly on the hybrid motor starter.
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