BECKWITH ELECTRIC M-3425A, Instruction Book

Page: 345 / 482

M‑3425A Instruction Book
6–58
81R Rate of Change of Frequency (#1, #2)
VOLTAGE INPUTS:
Configuration V1
CURRENT INPUTS:
None
TEST SETTINGS:
Pickup P Hz/Sec (0.10 to 20.00)
Time Delay D Cycles (3 to 8160)
Negative Sequence
Voltage Inhibit N % (0 to 99)
Programmed Outputs Z OUT (1 to 8)
Expanded I/O (9 to 23)
Test Setup:
1. It is recommended that the 81 Function be used to establish a window of operation for the 81R
Function which is smaller than the actual sweep range of the frequency applied. This is accomplished
as follows:

NOTE
: The frequencies given are suggested for testing rates below 10 Hz/Sec. Higher rates will require
consideration of the capabilities of the test equipment involved.
a. Enable the
81#1
with a unique Output assigned, a Pickup Setting of 1 Hz greater than the
minimum frequency of the ramp and a time delay and seal-in time setting at minimum (This
will result in an operational window that is free of erroneous Hz/Sec measurements when the
voltage source begins or ends the sweep.).
b. Enable the
81#2
with a unique Output assigned, a Pickup Setting of 1 Hz less than the maximum
frequency of the ramp and a time delay and seal-in time setting at minimum (This will result in
an operational window that is free of erroneous Hz/Sec measurements when the voltage source
begins or ends the sweep.).

NOTE
: Using this setup, it is important to remember that the 81 elements being used will be operating
in the 81R blocking regions, and the 81R contact operation must be distinguished from the
81 contacts.
F81#1 Block
81R Active Region
F81#2 Block
56.5 Hz 57.5 Hz 60 Hz 62.5 Hz 63.5 Hz
c. Utilizing a jumper, connect the
81#1
and
81#2
assigned Outputs to a unique Input.
d. Set the 81R Function to block on this input.
2. Determine the Function 81R Rate of Change of Frequency settings to be tested.
3. Enter the Function 81R Rate of Change of Frequency settings to be tested utilizing either the HMI
or IPScom Communications Software.
4. Disable all other functions prior to testing with the exception of Function 81. Refer to Section 4.4
System Setpoints, for details that describe disabling/enabling functions.

NOTE
: Testing of the 81R function requires a 3-phase voltage source capable of smoothly sweeping the
frequency of all voltages at a variable rate, continuously.
5. Connect test voltage inputs as shown in Figure 6-1, Voltage Inputs: Configuration V1.
6. Set the three-phase voltages V
A
, V
B
, and V
C
to the
Nominal Voltage
(nominal frequency).
The
Nominal Voltage
value previously input to the relay is described in Section 4.2, Setup System
and should be recorded on Figure A-2, Setup System Record Form.