REX640 includes two autoreclosing functions, each with up to

five programmable autoreclosing shots of desired type and

duration. A load-shedding function performs load shedding

based on underfrequency and the rate of change of the

frequency.

To validate correct closing conditions for a circuit breaker,

REX640 contains a synchrocheck function. For installations

including synchronous generators, REX640 introduces a

synchronizer that actively controls the generator’s voltage and

frequency in order to reach a synchronous situation across the

circuit breaker. The synchronizer functionality is available for a

generator circuit breaker as well as for a non-generator

(network) circuit breaker. A complete installation-wide

synchronizing system can be built using the REX640 relays. The

maximum size of the synchronizing system is eight generator

breakers and 17 non-generator breakers.