Siemens siprotec 7SJ63, Инструкция по эксплуатации

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Functions
6-107
7SJ63 Manual
C53000-G1140-C120-1
one start becomes possible without exceeding the excessive rotor temperature limit,
the blocking signal is terminated.
Therefore the restarting temperature related to trip temperature is expressed as:
Restarting Times When giving the maximum allowable cold and warm starting attempts , the motor man-
ufacturer assumes the motor is not restarted immediately after motor shutdown. This
is assumption is made because the distribution of heat in the rotor, is very different im-
mediately after motor shutdown. Only after a certain heat equilibrium time has passed
can a new starting attempt be made. The device can allow for the equilibrium time via
a programmable time interval entered at address 4304 T Equal. Each time the motor
is shutdown, the timer starts, and the calculated thermal profile of the rotor does not
change until this timer elapses. Once the time interval entered at address 4304 elaps-
es, the device assumes equilibrium has taken place in the rotor, and the thermal profile
begins to update. A time of zero can be entered at address 4304 at the option of the
user. The entire time that must elapse be fore motor starting can resume is equal to
the equilibrium time entered at address 4304 and the amount of time, calculated via
the thermal model, that it takes for the rotor temperature to decrease to the reset tem-
perature level.
Extending the Time
Constants In order to properly account for the reduced heat exchange when a self-ventilated mo-
tor is stopped, the cooling time constants can be increased relative to the time con-
stants for a running machine. A stopped motor is defined by current below an adjust-
able current flow monitoring threshold, assuming that the motor idle current is greater
than this threshold.
Logic If, under emergency conditions, motor starting in excess of the maximum allowable ro-
tor temperature must take place, the motor start blocking signal can be terminated via
a binary input, thus allowing a new starting attempt. The thermal rotor profile continues
to function, however, the maximum allowable rotor temperature will be exceeded. No
motor shutdown will be initiated by motor start blocking, but the calculated excessive
temperature of the rotor can be observed for risk assessment.
If the motor start blocking function is blocked or switched off, the thermal profile of the
excessive rotor temperature and the equilibrium time are reset, and any existing motor
start blocking signal is terminated.
Figure 6-47 shows the logic diagram of the start inhibit for motors function.
Θ
Restart
Θ
Trip
--------------------
n
cold
1 –
n
cold
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