ABB REF615C-E HCFFAEAGABC2BAA11E｜Feeder Protection and Control Relay｜

REF615C

The phase discontinuity protection function (PDNPSTOC1) provides protection against interruptions in the normal three-phase power supply.

It is primarily applied for detecting abnormal conditions such as:

Downed conductor situations
Open-phase faults
Loss of one phase in a three-phase feeder system
Severe phase imbalance caused by conductor interruption

The function monitors the three-phase current system and detects conditions where the normal phase relationship is disrupted.

Signal Connections

The operate signal from the phase discontinuity protection function is connected to:

Master Trip function
Alarm LED indication
Disturbance recorder

This ensures that:

The circuit breaker can be tripped when required
Local operators receive immediate fault indication
The event is captured for post-fault analysis
LED Indication

The phase discontinuity protection operate indication is assigned to:

LED 4

LED 4 is shared with the indication for:

Negative sequence overcurrent protection operation
Thermal Overload Protection (T1PTTR1)

The thermal overload protection function (T1PTTR1) provides protection and indication for feeder overload conditions.

The function evaluates thermal stress caused by excessive current loading and provides an alarm when the thermal capacity of the protected equipment is exceeded.

Typical applications include protection of:

Distribution cables
Transformers
Motors
Feeders
Other thermal-sensitive equipment
Signal Connections

The operate signal of the thermal overload protection function is connected to:

Master Trip function
Alarm LED indication

This allows the relay to:

Initiate protective action
Provide local warning indication
LED Indication

The thermal overload alarm indication is assigned to:

LED 5

Breaker Failure Protection (CCBRBRF1)

The breaker failure protection function (CCBRBRF1) provides backup protection in situations where the circuit breaker fails to interrupt fault current after receiving a trip command.

The function is initiated through the:

Start input

The start signal can be triggered by multiple protection functions within the REF615 IED, including:

Overcurrent protection stages
Earth-fault protection stages
Other trip-generating protection functions
Breaker Failure Operating Logic

The breaker failure protection evaluates:

Circuit breaker position status
Phase current measurements
Residual current measurements

Based on these conditions, the function determines whether the circuit breaker has successfully cleared the fault.

The breaker failure function supports different operating modes depending on:

Breaker auxiliary contact information
Current detection criteria
Protection application requirements
Breaker Failure Outputs

The breaker failure protection provides two separate operating outputs:

Output Function
TRRET Retrip command for the local circuit breaker
TRBU Backup trip command for upstream breaker
TRRET Output – Local Retrip

The TRRET operate output is used to retrip the same circuit breaker that initially received the trip command.

The signal is connected through:

Master Trip 2

Purpose:

Provides a second trip command
Increases the probability of successful breaker operation
Provides redundancy in the trip circuit
TRBU Output – Backup Trip

The TRBU operate output provides a backup trip signal to the upstream circuit breaker supplying the faulted feeder.

The signal is connected to:

Output PO2 (X100:8-9)

Purpose:

Clears the fault if the local breaker fails
Prevents prolonged fault current flow
Improves system protection reliability
LED Indications Summary
LED Function Indication
LED 4 Phase discontinuity protection operate / Negative sequence overcurrent operate
LED 5 Thermal overload protection alarm
LED 6 Breaker failure backup trip (TRBU) operate
Protection Signal Flow Overview
Phase Discontinuity Protection
Engineering Significance
Function Main Purpose Application Benefit
PDNPSTOC1 Detect phase interruption and imbalance Protects feeders against open-phase conditions
T1PTTR1 Detect thermal overload stress Prevents equipment overheating damage
CCBRBRF1 Detect breaker failure Provides high-speed backup fault clearing
TRRET Local breaker retrip Improves breaker clearing reliability
TRBU Upstream backup trip Maintains system protection coordination
LED assignments Local status indication Improves troubleshooting efficiency
Disturbance recording Fault analysis Supports commissioning and maintenance

The REF615 configuration integrates these protection functions into a coordinated feeder protection scheme, ensuring rapid fault clearing, equipment protection, and reliable backup operation in medium-voltage distribution networks.