CHAPTER 2: INSTALLATION
ELECTRICAL INSTALLATION
350 FEEDER PROTECTION SYSTEM – QUICKSTART GUIDE
57
Trip and Close output relays
The 350 relay is equipped with seven electromechanical output relays: two special relays
designed for Breaker trip and close (Relay 1 “Trip”, Relay 2 “Close”), four general purpose
relays (Auxiliary Relays 3 to 6), and a Critical Failure relay. The special purpose relays have
fixed operating characteristics and the general purpose relays can be configured by the
user.
Operation of the Trip and Close output relays is designed to be controlled by the state of
the circuit breaker as monitored by a 52a or 52b contact.
•
The Trip and Close relays reset after the breaker is detected in a state corresponding
to the command. When a relay feature sends a command to one of these special
relays, it will remain operational until the requested change of breaker state is
confirmed by a breaker auxiliary contact and the initiating condition has reset.
•
If the initiating feature resets, but the breaker does not change state, the output relay
will be reset after a default interval of 2 seconds.
•
If neither of the breaker auxiliary contacts, 52a nor 52b, is programmed to a contact
input, the Trip Relay is de-energized after either the delay programmed in the Breaker
Failure feature, or a default interval of 100 ms after the initiating input resets. The
Close Relay is de-energized after 200 ms.
•
If a delay is programmed for the Trip or Close contact seal-in time, then this delay is
added to the reset time. Note that the default setting for the seal-in time is 40 ms.
Breaker monitoring (Trip and Close coil monitoring) is performed by a built-in voltage
monitor on Form A output relays: #1 Trip, and #2 Close. The voltage monitor is connected
across each of the two Form A contacts, and the relay effectively detects healthy current
through the circuit. In order to do this, an external jumper must be connected between
terminals A2 and A3 for Trip coil monitoring, or/and B4, and B5 for Close coil monitoring.
As long as the current through the Voltage Monitor is above the threshold of the trickle
currents (see Technical Specification for Form A output relays), the circuit integrity for the
Trip (Close) coil is effectively normal. If the Trip (Close) coil circuit gets disconnected, or if in
general a high resistance is detected in the circuitry, a Trip (Close) alarm will be set and the
“ALARM” and “MAINTENANCE” LEDs will be on.
Example 1
: The figures below show the two different connections of the breaker trip (close)
coil to the relay’s trip output #1 terminals (output #2 Close coil monitoring) for both no
voltage monitoring and voltage monitoring of the trip (close) circuit integrity.
NOTE
NOTE:
To monitor the trip coil circuit integrity, use the relay terminals A2 and B3 to connect the
Trip coil, and provide a jumper between terminals A2 (optional voltage) and A3.
52a Contact
Configured
52b Contact
Configured
Relay Operation
Yes
Yes
Trip Relay remains operational until 52b indicates an
open breaker. Close Relay remains operational until 52a
indicates a closed breaker.
Yes
No
Trip Relay remains operational until 52a indicates an
open breaker. Close Relay remains operational until 52a
indicates a closed breaker.
No
Yes
Trip Relay remains operational until 52b indicates an
open breaker. Close Relay remains operational until 52b
indicates a closed breaker.
No
No
Trip Relay operates until either the Breaker Failure delay
expires (if the Breaker Failure element is enabled), or 100
ms after the feature causing the trip resets. Close Relay
operates for 200 ms.
