Current Transformer Supervision - Allen-Bradley Rockwell Automation 857 User Manual

4-10
Supporting Functions
Current Transformer
Supervision
857-UM001A-EN-P – July 2009
Table 4.7 – Setting Parameters of the Voltage Sag Measurement Function
Parameter Value
U1< 10.0 ... 120.0
Period 8h
Day
Week
Month
Date
Time
Table 4.8 – Measured and Recorded Values of Voltage Sag Measurement Function
Parameter
Measured Voltage
value
U1
Recorded Count
values
Prev
Total
Prev
The device supervise the external wiring between the device
terminals and current transformers (CT) and the CT them selves.
Furthermore, this is a safety function as well, since an open
secondary of a CT, causes dangerous voltages.
The CT supervisor function measures phase currents. If one of
the three phase currents drops below I
phase current is exceeding the I
issue an alarm after the operation delay has elapsed.
Table 4.9 – Setting Parameters of CT Supervisor: CTSV ( )
Parameter Value
Imax> 0.0 ... 10.0
Imin< 0.0 ... 10.0
t> 0.02 ... 600.0
CT on On; Off
CT off On; Off
Unit Default
% 64 Setting value
- Month Length of the observation period
- - Date
- - Time
Value Unit
LOW; - Current voltage status
OK
% Measured positive sequence
voltage
- Number of voltage sags during
the current observation period
- Number of voltage sags during
the previous observation period
s Total (summed) time of voltage
sags during the current
observation period
s Total (summed) time of voltage
sags during the previous
observation period
< setting, while another
min
> setting, the function will
max
Unit Default
xIn 2.0 Upper setting for CT supervisor
xIn 0.2 Lower setting for CT supervisor
s 0.10 Operation delay
- On CT supervisor on event
- On CT supervisor off event
Description
Description
Description