ABB REF615E_E HBFHAEAGNBA1BNN1XE｜Feeder Protection and Control Relay｜

REF615C

1. Phase Discontinuity Protection (PDNPSTOC1)

The phase discontinuity protection (PDNPSTOC1) provides protection against interruptions in the normal three-phase load supply. It is mainly intended to detect abnormal conditions where one phase is lost or disconnected, such as:

Downed conductor situations
Broken phase conductors
Open-circuit faults in three-phase feeder systems
Loss of one phase in an energized load circuit

The function detects phase imbalance conditions caused by discontinuity in the three-phase supply.

Signal Connections

The operate signal from PDNPSTOC1 is connected to:

Master Trip
→ Initiates a feeder circuit breaker trip when phase discontinuity is detected.
Alarm LED
→ Provides local visual indication of protection operation.
Disturbance Recorder
→ Records the event and associated electrical data for post-fault analysis.
LED Indication
LED 4
Used for:
Phase discontinuity protection operation indication
Negative sequence overcurrent protection operation indication
2. Thermal Overload Protection (T1PTTR1)

The thermal overload protection (T1PTTR1) provides monitoring and protection against excessive thermal stress caused by sustained overcurrent conditions.

Typical applications include:

Cable thermal protection
Transformer feeder protection
Motor feeder overload monitoring
Protection against long-duration overload currents

Unlike instantaneous overcurrent protection, thermal overload protection considers the heating effect of current over time.

Signal Connections

The operate signal from T1PTTR1 is connected to:

Master Trip
→ Initiates breaker tripping when the thermal limit is exceeded.
Alarm LED
→ Provides local overload alarm indication.
LED Indication
LED 5
Used for:
Thermal overload protection alarm indication
3. Circuit Breaker Failure Protection (CCBRBRF1)

The breaker failure protection (CCBRBRF1) provides backup protection when a circuit breaker fails to clear a fault after receiving a trip command.

Breaker failure protection is initiated through the START input, which can be activated by multiple protection functions inside the IED, including:

Overcurrent protection stages
Earth-fault protection stages
Phase discontinuity protection
Other configured trip-producing functions
Breaker Failure Operating Modes

The CCBRBRF1 function supports different operating modes based on:

Circuit breaker auxiliary position signals
Phase current measurement
Residual (earth-fault) current measurement

The IED determines whether the breaker has successfully interrupted the fault current by monitoring:

Breaker open/closed status
Remaining fault current
Protection trip conditions
Breaker Failure Outputs

The breaker failure protection provides two main output signals:

Output Function Application
TRRET Retrip output Trips the same circuit breaker again through Master Trip 2
TRBU Backup trip output Sends trip command to upstream breaker
TRRET — Retrip Function

The TRRET operate output is connected to:

Master Trip 2

Purpose:

Provides a second trip command to the failed breaker.
Attempts to clear the fault locally before initiating upstream isolation.

Typical sequence:

Protection detects fault.
Main trip command issued.
Breaker fails to open.
Breaker failure timer expires.
TRRET sends retrip command.
TRBU — Backup Trip Function

The TRBU operate output provides backup clearing of the fault by tripping the upstream supply breaker.

Signal connection:

TRBU → Output PO2 (X100:8-9)

Purpose:

Disconnects the upstream source feeding the failed breaker.
Ensures fault clearance when local breaker operation is unsuccessful.
LED Indication
LED 6
Used for:
Backup trip (TRBU) operation indication
Protection Signal Summary
Protection Function Function Block Main Purpose Output Connection LED
Phase Discontinuity Protection PDNPSTOC1 Detects loss of phase / three-phase supply interruption Master Trip + Alarm + Disturbance Recorder LED 4
Thermal Overload Protection T1PTTR1 Protects against excessive thermal loading Master Trip + Alarm LED 5
Breaker Failure Protection CCBRBRF1 Provides backup clearing when breaker fails TRRET → Master Trip 2; TRBU → PO2 X100:8-9 LED 6
Engineering Application Summary

This configuration provides a complete feeder protection scheme combining:

Primary feeder protection
Overcurrent and earth-fault protection
Phase discontinuity protection
Thermal overload protection
Breaker backup protection
Local breaker retrip
Upstream breaker backup trip
Operational visibility
LED indication
Disturbance recording
Alarm signaling

This arrangement is typical for medium-voltage feeder protection IEDs, ensuring both equipment protection and system reliability during abnormal operating conditions.