2–35
Application - 2
60FL Fuse Loss
Since some functions may inadvertently operate
when a VT fuse is blown, provisions are incorporated
for both internal and external fuse loss detection.
Functions which misoperate on VT fuse loss such
as 21, 32, 51V, 67, and 67N can be programmed to
disable during a VT fuse-loss condition. The status
of the fuses can then be monitored using remote
communications or locally if the optional M-3931
HMI Module is in service.
For internal detection of a fuse-loss condition,
positive and negative sequence quantities are
compared. The presence of negative sequence
voltage in the absence of negative sequence current
is considered to be a fuse loss condition. An
additional supervising condition includes a minimum
positive sequence voltage to assure VT inputs are
being applied to the relay.
A timer, associated with the fuse loss logic, is
available, to assure proper coordination for
conditions which may appear as a fuse loss such
as secondary VT circuit faults which will be cleared
by local low voltage circuit action.
For the specific application where the above logic
cannot be considered reliable (such as when current
inputs to the relay are not connected, sustained
positive sequence current during fault conditions is
minimal, or negative sequence currents are not
present during fault conditions), provision is made
for disabling the 60FL Fuse Loss internal logic by
not selecting “FL” from the 60FL Input Initiate
choices.
Provision is also made in the relay to input external
status contact(s) of other fuse loss detection
protection. These external contacts may be input to
any of the input contacts (IN1 to IN6) and
programmed to initiate the 60FL function.
Save
Cancel
@ : WARNING, Function DISABLED until output selected!
(60FL) - VT FUSE-LOSS DETECTION
Time Delay:
1 Cycle
8160 Cycles
60FL
OUTPUT
8
7
6
5
4
3
2
1
@
FL
6
5
4
3
2
1
Blocking Input
FL
6
5
4
3
2
1
Input Initiate
Figure 2-25
M-3822 IPScom
®
for Windows™ Fuse Loss (60FL) Setpoint Ranges
Path
: Relay Menu/Setup/Setpoints/(60FL) Fuse-Loss Detection
COMMAND BUTTONS
Save
Save
s all information to the relay.
Cancel
Returns the user to the previous window; any changes to the displayed information are lost.
The initiating inputs are user-designated. The operation of
any of the externally-connected contacts (across these
M-3520 inputs) will start the associated time delay to the
60FL function operation.
The time delay is to be set to coordinate for conditions
which may appear as a fuse loss but will be corrected by
other protection (such as a secondary VT circuit fault which
will be cleared by low voltage circuit action).
60FL INPUT INITIATE
FL i6 i5 i4 i3 i2 i1
60FL DELAY
________ Cycles
If this function is enabled, the following settings are applicable:
Summary of Contents for M-3520
Page 1: ...Instruction Book M 3520 Intertie Protection Relay ...
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