Siemens siprotec 7SA522 User Manual page 138

Configuration
Example 1 (MW):
Low Current
Monitor
Example 2:
Isolation Switch
Interlocking
5-40
A few examples are given below.
A configuration for low-current monitoring alarm (see Figure 5-37) which can be pro-
duced using CFC, should be a first example. This element may be used to detect op-
eration without load, or to recognize open circuited conditions. By connecting meas-
ured current values with a limit function via an OR function, an indication may be gen-
erated which can be used to cause switching operations.
• The configuration sheet is assigned to task level MW_BEARB.
• Four function modules (3 lower-value limit modules and an OR gate), are taken
from the function module library and copied into the configuration sheet.
• In the left panel, the measurement values to be monitored (I
nominal current) are each selected and connected with the measured value inputs
of each limit module function.
• A lower limit setpoint value (IL<) is linked with the limit inputs of each of three limit
sensor functions.
• The limit value function outputs are passed on to the OR gate.
• The output of the OR gate is connected to the right border column at annunciation
", DODUP".
The limit value message is triggered when the preset limit value is below the setpoint
(low current) in at least one of the three phases. The hysteresis of the limit values is
fixed and need not be entered (5 % of set point plus 0.5 % of nominal value).
Measurement
IL1
Set points
IL<
Measurement
IL2
Set points
IL<
Measurement
IL3
Set points
IL<
Figure 5-37 Under-current monitoring as an example of user defined measurement value
processing
Interlocking logic (see Figure 5-38) is to be implemented for the operation of an isolat-
ing switch using function key 4. The user must take the switch position indications of
the corresponding isolation switch and the grounding switch into account. The CLOSE
and TRIP indications from the auxiliary contacts of each switch are used.
• Function modules NOR (2 required), XOR, and AND are taken from the library and
copied into the working page.
FM:
Lower
Setpoint
FM:
FM:
Lower
>1
Setpoint
FM:
Lower
Setpoint
, I , I in % of the
L1 L2 L3
I<
alarm OUT
7SA522 Manual
C53000-G1176-C119-2