rated current as reference. The parameters are determined by the starting-time characteristic curve of the
motor.
You can find more information in chapter 6.50 Motor-Starting Time Supervision in the SIPROTEC 5, 7UM85
Device Manual.
Motor Restart Inhibit
The Motor restart inhibit function is used to prevent the motor from a further start. 1 Thermal stage, 1
Counter stage, and 1 Timer stage can operate simultaneously within this function.
If the motor changes to
Standstill
state, the
Restart inhibit
signal becomes active under one of the
following conditions:
•
The rotor temperature exceeds the restart limit in a Thermal stage.
•
The rotor is in the equilibrium process in a Thermal stage.
•
The maximum permissible number of starts (parameter
Perm. no. of starts
) within a set time
interval (parameter
Time interval (per.starts)
) is reached in a Counter stage.
•
The time interval from the most recent start to the motor state change is less than the setting value
Min.
time between starts
in a Timer stage.
During the normal operation, the explosion-proof motors can be started twice from the cold rotor state and
once from the warm rotor state. In general, a sufficient long cooling time must be observed.
For the protection device which is used as the protection of explosion-proof motors, the parameter Equili-
brium time must not be set to 0.0 min.
i
i
NOTE
The restart inhibit is stopped when the following conditions are fulfilled:
•
The auxiliary voltage supply fails.
•
The failure time of the auxiliary voltage supply is longer than the compensation time of the device
while the Motor restart inhibit function is operating.
You can find more information in chapter 6.51 Motor Restart Inhibit in the SIPROTEC 5, 7UM85 Device
Manual.
Load-Jam Protection
The Load-jam protection function protects the motor in case of sudden rotor locking or a jump in load
increase. A quick motor shutdown avoids or reduces damage to drives, bearings, and other mechanical motor
components.
The rotor locking results in a jump in current increase in the phases. The current jump is used by the function
as a recognition criterion.
The Thermal overload protection rotor function can also pick up as soon as the configured threshold values
of the thermal replicas are exceeded. Because of the important stator time constants, this takes much more
time. The Load-jam protection function, however, can detect a locked rotor quickly, thus reducing possible
damage to the motor and to the powered equipment.
You can find more information in chapter 6.57 Load-Jam Protection Motor in the SIPROTEC 5, 7UM85 Device
Manual.
Thermal Overload Protection
The Thermal overload protection function creates a thermal replica of the protected equipment. If the initial
adjustable overtemperature threshold
Threshold thermal warn.
is exceeded, a warning indication is
issued. If the overtemperature limit (tripping overtemperature) is exceeded, an operate indication is issued
immediately and the equipment is disconnected from the power supply.
Application and Setting Notes
16
SIPROTEC 5, Additional Information on the Protection of Explosion-Proof Motors with Type of Protection Increased Safety e,
Manual
C53000-H5050-C078-1, Edition 03.2019
