ABB REB500 Additional features Distributed busbar protection

Additional features

Self-supervision

All the system functions are continuously monitored to ensure the maximum reliability and availability of the

protection. In the event of a failure, incorrect response or inconsistency, the corresponding action is taken to

establish a safe status, an alarm is given and an event is registered for subsequent diagnostic analysis.

Important items of hardware (e.g. auxiliary supplies, A/D converters and main and program memories) are

subjected to various tests when the system is switched on and also during operation. 

A watchdog continuously monitors the integrity of the software functions and the

exchange of data via the REB500 process bus is also continuously supervised.

Extension of the system

The system functions are determined by software,configured using the software configuration tool.

The system can be completely engineered in advance to correspond to the final state of the station. 

The software modules for new bays or features can be activated using

the HMI500 when the primary plant is installed or the features are needed.

Additional system functions, e.g. breaker failure or end fault protection can be easily activated at any time without extra hardware.

Resetting the trip commands/signals

The following resetting modes can be selected for each binary output (tripping or signal outputs):

· Latches until manually reset

· Resets automatically after a delay

Inspection/maintenance

A binary input can be assigned that excludes a bay unit from evaluation by the protection system. 

It is used while performing maintenance or inspection activities on the primary equipment respectively.

Redundant power supplies (Optional)

The central unit may be ordered with a redundant power supply.

Time synchronization

The absolute time accuracy with respect to an external time reference depends on the method of synchronization

7. Requirements

Optical fiber cables

A distributed busbar protection layout requires optical fiber cables and connectors with the following characteristics:

· 2 optical fiber cores per bay unit

· glass fibers with gradient index

· diameter of core 62.5/50 µm, sheath 125 µm

· maximum permissible attenuation ≤ 8 dB/6dB

· LC connector (for 62.5/50 µm optical fibers)

· rodent protected and longitudinally waterproof if in cable ducts

Please observe the permissible bending radius when laying the cables.

The following attenuation figures are typical values which may be used to determine an approximate attenuation

balance for each bay:

Isolator auxiliary contacts

Auxiliary contacts on the isolators are connected to binary inputs on the bay units and control the status of the

busbar replica in the numerical busbar protection.

One potentially-free N/O and N/C contact are required on each isolator. 

The N/O contact signals that the isolator is ‘CLOSED’ and the N/C contact that the isolator is ‘OPEN’.

During the closing movement, the N/O contact must close before the isolator main contact gap reaches its flashover point.