Siemens siprotec 7SA6 User Manual page 167

Example 1 (MW):
Low Current
Monitor
7SA6 Manual
C53000-G1176-C133-1
Figure 5-41 Warning message on reaching the limits
A few examples are given below.
A configuration for low-current monitoring alarm (see Figure 5-42) which can be
produced using CFC, should be a first example. This element may be used to detect
operation without load, or to recognize open circuited conditions. By connecting
measured current values with a limit function via an OR function, an indication may be
generated 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).
Configuration
, I , I in % of the
L1 L2 L3
5-43