ABB SPAJ 110 C-DA Earth-fault relay

ABB SPAJ 110 C-DA  Earth-fault relay

Description

The earth-fault relay SPAJ 110 C is a secondary relay that is connected to the current transformers of the object to be protected. The earth-fault current can be measured either via a set of three phase current transformers in a residual current connection or a window-type core-balance current transformer. When a core-balance current transformer is used, it should be secured that the repeatability of the current transformer is sufficient also at high earth-fault currents. When an earth-fault occurs, the relay delivers an alarm signal, trips the circuit breaker or starts an external auto-reclose relay, depending on the application and the configuration of the relay.

When the energizing current exceeds the set start value I0> of the low-set stage, the earthfault relay starts. When, at definite time operation, the set operate time t> or, at IDMT operation, the calculated operate time t>, expires, the relay operates. In the same way the high-set stage starts once its set start value I0>> is exceeded and, when the set operate time t>> expires, the relay operates.

The low-set stage of the earth-fault relay can be given either definite-time or inverse-time characteristic. At inverse time characteristic four inverse time curve sets with different degrees of inversity are available: Normal inverse, Very inverse, Extremely inverse and Long-time inverse. These curve sets comply with the BS 142 and IEC 60255 standards.

The start signal from the earth-fault relay is received as contact function. The start signal can be used, for instance, for blocking cooperating protection relays.

The relay contains one optically isolated logic input for incoming external control signals, generally blocking signals.

Features

Low-set neutral overcurrent stage with definite time or inverse time characteristic

High-set neutral overcurrent stage with definite time characteristic

Output relay functions to be freely configured

Flexible adaptation to different types of application

Serial interface for connecting the relay to a fibre optic object bus and substation and network control systems

Digital display of setting values, neutral current measured, memorized fault values, etc.

Continuous self-supervision with auto-diagnostics of hardware and software

Technical Specifications