Cover unused inputs with dust caps.
Arc protection with one protection relay
In installations, with limited possibilities to realize signalling between protection
relays protecting incoming and outgoing feeders, or if only the protection relay
for the incoming feeder is to be exchanged, an arc protection with a lower
protective level can be achieved with one protection relay. An arc protection with
one protection relay only is realized by installing two arc lens sensors connected to
the protection relay protecting the incoming feeder to detect an arc on the busbar.
In arc detection, the arc protection stage trips the circuit breaker of the incoming
feeder. The maximum recommended installation distance between the two lens
sensors in the busbar area is six meters and the maximum distance from a lens
sensor to the end of the busbar is three meters.
Figure 392: Arc protection with one protection relay
Arc protection with several protection relays
When using several protection relays, the protection relay protecting the outgoing
feeder trips the circuit breaker of the outgoing feeder when detecting an arc at the
cable terminations. If the protection relay protecting the outgoing feeder detects
an arc on the busbar or in the breaker compartment via one of the other lens
sensors, it will generate a signal to the protection relay protecting the incoming
feeder. When detecting the signal, the protection relay protecting the incoming
feeder trips the circuit breaker of the incoming feeder and generates an external
Protection functions
1MRS757644 H
752
620 series
Technical Manual
