3.6 Other AC protections
3.6.1 Lockout relay (ANSI 86)
The lockout relay ensures that the alarm action continues for an alarm, until the lockout relay is reset. The controller can function as
a lockout relay for alarm conditions which have the
Latch
parameter enabled. The protection is in effect until the alarm condition is
cleared, the alarm acknowledged and the latch is reset.
The lockout relay applies to all latched alarms, and does not activate a specific alarm or have any inhibits.
Protection
IEC symbol (IEC60617)
ANSI (IEEE C37.2)
IEC 61850
Operate time
Lockout relay
86
Dependent on protection
Alarm
condition
Acknowledge
alarm
Controller
protection
active
Clear latch
Latch
Alarm
(1)
(3)
(4)
(5)
(6)
(2)
t1
1.
Alarm condition
: When an alarm condition occurs, an alarm-dependent delay timer activates. If the alarm condition occurs for
longer than the delay timer, the protection activates.
2.
Controller protection
: If a latch is enabled for the protection, the latch activates when the controller protection activates. The
protection will remain active until the latch is reset, even if the alarm condition clears.
3.
Alarm
: The alarm output, for example, an alarm horn, remains active until the alarm is acknowledged. When the alarm is
acknowledged, the protection remains active if a latch is enabled.
4.
Acknowledge alarm
: The alarm can be acknowledged while the alarm condition is still active, or when the alarm condition has
cleared. If a latch is active and the alarm is acknowledged after the alarm condition has cleared, the protection will remain active.
5.
Alarm latch
: If a latch is enabled for the alarm, the alarm latch will activate when the controller protection activates. While the
latch is active, the alarm protection will also be active.
6.
Clear alarm latch
: The alarm latch can only be removed once the alarm condition is no longer active and the alarm is
acknowledged. The protection will remain active until the latch is cleared.
For most alarms, a latch can be
Enabled
as a parameter under
Configure > Parameters > [Alarm location] > [Alarm] > Latch
.
[Alarm location] is the location of the alarm parameters, for example,
Busbar > Voltage protections
. [Alarm] is the alarm name.
CAUTION
If the controller is unpowered, the controller relays will de-energise.
DESIGNER'S HANDBOOK 4189340911K UK
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