Motor Restart Inhibit 66 - Siemens SIPROTEC 4 User Manual

Functions
2.8 Motor Protection
[formel-taus-tmaxanlauf-150502-kn, 1, en_US]
At 80% of nominal voltage (which corresponds to 80% of nominal starting current), the tripping time is:
[formel-taus-133-150502-kn, 1, en_US]
After the time delay (4104 LOCK ROTOR TIME) has elapsed, the binary input becomes effective and gener-
ates a trip signal. If the locked rotor time is set just long enough that during normal startup the binary input
>48 Rot. locked (FNo. 6805) is reliably reset during the delay time 4104 LOCK ROTOR TIME, faster trip-
ping will be available during motor starting under locked rotor conditions.
Threshold Values "cold" / "warm" Motor
Parameter 4106 TEMP.COLD MOTOR determines the threshold value. It is derived from the number of cold
(n ) and warm (n
cold
Unless specified otherwise, three cold and two warm startups (n
typical motor data. The limit value is thus derived:
[fo_T-motorl-grenzwert-oangaben, 1, en_US]
A recommended setting value with consideration of a safety margin for TEMP.COLD MOTOR = 25%.
Should the technical data of the motor make reference to four cold and two warm startups (n
2), the following limit value can be determined:
[fo_T-motorl-grenzwert-mangaben, 1, en_US]
The setting value should fall below the limit value. A value of 40% is recommended for that purpose.
NOTE
i i
Overload protection curves are also effective during motor starting conditions. However, the thermal
profile during motor starting is constant. Parameter I MOTOR START at address 1107 limits the working
range of the overload protection to larger current values.
NOTE
i
i
The motor restart inhibit 4301 FCT 66 must be switched on to enable distinguishing between cold and
warm condition of the motor.
2.8.2

Motor Restart Inhibit 66

The motor restart inhibit prevents restarting of the motor when this restart may cause the permissible thermal
limits of the rotor to be exceeded.
Additionally, the function can trip directly if the rotor temperature exceeds the maximum admissible tempera-
ture (100%) (rotor overload).
148
) motor startups.
warm
= 3; n = 2) will be sufficient. These are
cold warm
SIPROTEC 4, 7SJ62/64, Manual
C53000-G1140-C207-8, Edition 08.2016
= 4; n =
cold warm