Allen-Bradley 857-RAA, User Manual

Page: 28 / 42

28 Rockwell Automation Publication 857-UM002C-EN-P - February 2018
Chapter 4 Configure the Base 857 Relay
Linked Val. Min See Configure the 857-RAD Analog Outputs
on page 35
AO Link’s user defined Minimum
Value Allows scaling of the mA Output parameter
Linked Val. Max See Configure the 857-RAD Analog Outputs
on page 35
AO Link’s user defined maximum
value Allows scaling of the mA Output parameter.
Ao Slave address 1…247 RTD Modbus slave address Value must match the hardware Address ss defined by the
switches on the 857-RAD
Ao Modbus address See Configure the 857-RAD Analog Outputs
on page 35
1

318
2

319
3

320
4

321
Although there are 16 locations available, only 4 can be assigned
(857-RAD). Addresses are by default numbered from 1 to 16.
However the address value must be set according to the Modbus
registers values, meaning that:
Analog Output 1 — Modbus 318
Ao Register type HoldingR Holding register According to the Modbus Protocol a Holding Register is a 16-bit
word register which can be read or written.
Modbus Min See Configure the 857-RAD Analog Outputs
on page 35
This is the minimum value which is
sent to the 857-RAD via Modbus
protocol in order to set the minimum
value for the mA Min parameter. Typical values;
mA Min = 0 is equal to a Modbus Min = 0
The relationship between these two parameters is 1:1000.
See
Configure the 857-RAD Analog Outputs on page 35 .
Modbus Max See Configure the 857-RAD Analog Outputs
on page 35
This is the maximum value which is
sent to the 857-RAD via Modbus
protocol in order to set the maximum
value for the mA Max parameter. Typical values;
mA Max = 20 is equal to a Modbus Max = 20000
The relationship between these two parameters is 1:1000.
See
Configure the 857-RAD Analog Outputs on page 35
AO Counter 0 … Error counter for AO It increments itself if either AO Slave Address or Ao Register
Address are not set correctly
Table 10 - 857-RAD External Analog Outputs Parameter Setup (Continued)
Parameter Value Explanation Notes
Table 11 - Measurands that can be Assigned to Analog Outputs
Measurement Value Description Extended Description Measurand
P Active power Real power [kW]
Q Reactive power Reactive power flow [kvar]
S Apparent power Root-mean-square (rms) current by the root-mean-square voltage [kVA]
P.F. Power factor Measured power factor -1 to 1
f Frequency Measured frequency [Hz]
cosphi Cosine phi (kW/kVA) - 1 to 1
IL1 Phase current IL1 Phase A current [A]
IL2 Phase current IL2 Phase B current [A]
IL3 Phase current IL3 Phase C current [A]
IL Average current (IL1+IL2+IL3)/3 Motor or feeder average current [A]
U12 Phase-to-phase voltage U12 Line-to-line voltage [V]
U23 Phase-to-phase voltage U23 Line-to-line voltage [V]
31 Phase-to-phase voltage U31 Line-to-line voltage [V]
UL Average for the three phase voltages Line to Line Average Voltage (LL) [V]
UL1 Phase-to-earth voltage UL1 Phase-to-ground voltage [V]
UL2 Phase-to-earth voltage UL2 Phase-to-ground voltage [V]
UL3 Phase-to-earth voltage UL3 Phase-to-ground voltage [V]
UPhase Average Voltage (UL1+UL2+UL3) Line to Neutral Average Voltage (LN) [V]
IFault Latest overcurrent fault level Pu value of current [pu]