Siemens SIPROTEC 4 7SJ61 Manual page 105

The following settings are made:
IStart/IMOTnom = 4.9
I MOTOR NOMINAL = 0.6 A
T START MAX = 8.5 s
MAX.WARM STARTS = 2
#COLD-#WARM = 1
For the rotor temperature equilibrium time, (address 4304) a setting time of approx. T Equal = 1 min has
proven to be a good value. The value for the minimum inhibit time T MIN. INHIBIT depends on the motor
manufacturer, or by the user's requirements. It must in any case be higher than 4304 T Equal. In this
example, a value has been chosen that reflects the thermal replica (T MIN. INHIBIT = 6.0 min).
The motor manufacturer's, or the requirements also determine also the extension factor for the time constant
during cool-down, especially with the motor stopped. Where no other specifications are made, the following
settings are recommended: Kτ at STOP = 5 and Kτ at RUNNING = 2.
For a proper functioning, it is also important that the CT values and the current threshold for distinction
between stopped and running motor (address 212 BkrClosed I MIN, recommended setting ≈ 0.1 Ι
have been set correctly. An overview of parameters and their default settings is generally given in the setting
tables.
Temperature Behavior during Changing Operating States
For a better understanding of the above considerations several possible operating ranges in two different
operating areas will be discussed in the following paragraph. Settings indicated above are to be used prevaling
3 cold and 2 warm startup attempts have resulted in the restart limit reaching 66.7%.
A) Below the thermal restarting limit:
•
A normal startup brings the machine into a temperature range below the thermal restarting limit and the
machine is stopped. The stop launches the equilibrium time 4304 T Equal and generates the message
66 TRIP . The equilibrium time expires and the message 66 TRIP is cleared. During the time T Equal
the thermal replica remains "frozen" (see
•
A normal startup brings the machine into a temperature range below the thermal restarting limit, the
machine is stopped and is started by an emergency startup without waiting for the equilibrium time to
expire. The equilibrium time is reset, the thermal replica is released and
(see Figure
SIPROTEC 4, 7SJ61, Manual
C53000-G1140-C210-6, Edition 05.2016
2-36, to the right).
Figure 2-36, on the left).
Functions
2.6 Motor Protection
MOT.NOM
66 TRIP is reported as going
)
105