Voltage Measurement Mode - Allen-Bradley Rockwell Automation 857 User Manual

Maximum Values of the
Last 31 Days and Twelve
Months

Voltage Measurement Mode

Some maximum and minimum values of the last 31 days and the last
twelve months are stored in the non-volatile memory of the device.
Corresponding time stamps are stored for the last 31 days. The
registered values are listed in the following table.
Table 5.12 – Registered Values
Measurement Max Min
IL1, IL2, IL3 X
Io1, Io2 X
S X
P X X
Q X X
The value can be a one cycle value or an average according
parameter "Timebase".
Table 5.13 – Parameters of the Day and Month Registers
Parameter Value
Timebase Parameter to select the type of the registered values.
20 ms
Collect min & max of one cycle values
200 ms
Collect min & max of 200 ms average values
1 s
Collect min & max of 1 s average values
1 min
Collect min & max of 1 minute average values
demand
Collect min & max of demand values (see "Demand
Values")
ResetDays Reset the 31 day registers
ResetMon Reset the 12 month registers
This is the fundamental frequency rms value of one cycle updated every 20 ms.
Depending on the application and available voltage transformers, the
device can be connected either to line-to-line voltages or phase-to-
ground voltages. The configuration parameter "Voltage measurement
mode" must be set according the used connection.
The available modes are:
•
"2LL+Uo"
The device is connected to line-to-line voltages U
and to zero sequence voltage U
are calculated. The network must use only three wires. Any
neutral wire must not exist.
•
"3LN"
The device is connected to phase-to-ground voltages U
U and U . The zero sequence voltage is calculated. A
L2 L3
neutral wire may exist.
Measurement Functions
Description
Phase current (fundamental frequency value)
Residual current
Apparent power
Active power
Reactive power
Description
. The phase-to-ground voltages
0
857-UM001A-EN-P – July 2009
5-5
Set
S
S
S
and U
12 23
,
L1