Settings For Thermal Overload Protection - Siemens SIPROTEC 7SJ62 Instruction Manual

Functions
Extension of Time
Constants
Emergency Starting
Motor Starting Rec-
ognition
6.9.2.1

Settings for Thermal Overload Protection

Addr. LCD-Text
4201 FCT 49
4202 49 K-FACTOR
4203 TIME CONSTANT
49 Θ ALARM
4204
4205 I ALARM
4207 Kτ-FACTOR when
motor stops
4208
T EMERGENCY
6-104
culated operating temperature falls below the warning level, thus allowing the protect-
ed equipment to be placed back into service.
The thermal warning level is given in % of the tripping temperature level (maximum
allowable operating temperature).
A current warning level is also available (, $/$50 ). The setting at address 
corresponds to secondary amperes, of course, and should be set equal to, or slightly
less than, permissible continuous current (k * I
used in lieu of the thermal warning level by setting the thermal warning level to 100 %.
The time constant programmed at address 4203 is valid for a running motor. For cy-
cling motors without external cooling, the motor loses heat more slowly. For a cycling
motor, the 7SJ62 takes the reduced heat loss into account by increasing the time con-
stant τ by a programmable factor kτ (set at address ). If no distinguishing of the
time constants is necessary (e.g. externally-cooled motors, cables, transformers, etc.)
the .τ )$&725 is set at  (Default Setting value).
The drop-out time to be entered at address 4208 must be sufficient to allow the calcu-
lated operating temperature to decrease below the drop out level.
To ascertain whether or not a motor is starting, the motor currents are compared with
the setting at address . If the motor currents exceed the setting at address ,
a motor starting condition is assumed. Information on how to set address  is giv-
en in Subsections 6.1.3 and 6.8.2.
In the list below, the setting range and default setting value for I ALARM is for a device
with a nominal current rating I
Setting Options values and Default Setting value by 5. Consider the current transform-
er ratios when setting the device with primary values.
Setting options
OFF
ON
Alarm only
0.10 ~ 4.00
1.0 ~ 999.9 min
50 ~ 100%
0.50 ~ 20.00 A
1.0 ~ 10.0
10 ~ 15000 sec
. The current warning level may be
Nsec)
= 5 A. For a nominal current rating I
N
Default Setting
OFF 49 Thermal overload protection
1.10 49 (Service Factor k)
100.0 min Time Constant
90% 49 Thermal warning stage
5.00 A Current warning stage
1.0 Kτ time factor for non-running
motor
100 sec Dropout time after emergency
start-up
= 1 A, divide the
N
Comment
7SJ62 Manual
C53000-G1140-C121-1