Description
2.3 Protection system
3WA1 air circuit breaker
Equipment Manual, 02/2023, 92310000002-06
73
Maintenance mode DAS+
Fast tripping of circuit breakers and extinction of the arc are extremely important in order
to protect staff working in the immediate vicinity of live parts.
To this end, the maintenance mode DAS+ operates with its own set of protection
parameters to reduce the trip threshold, thus ensuring that the circuit breaker trips at a
lower threshold than would be necessary for normal operation and without delay times.
The maintenance mode DAS+ is an energy-reducing function with local status
indication, which is used to comply with the following norms/standards:
• National Electrical Code (NEC) Section 240.87 (B) (3) Arc-Flash energy reduction
(Energy-reducing maintenance switching with local status indicator)
• NFPA 70E Standard for Electrical Safety in the Workplace
• DIN EN 50110-1 Operation of electrical installations/B.6 Arc hazard
DAS+ system
The following shows how to integrate several circuit breakers in the maintenance mode
DAS+. The activation is done via a switch. The activated maintenance mode on all the
circuit breakers is signaled by a "DAS+ active" light. If this message is to be output with
very small currents of one or more circuit breakers or open circuit breakers, the
electronic trip unit must be additionally supplied with an external auxiliary voltage of
24 V DC for signaling.
(1) To ensure proper performance, the total cable length of the system must not exceed
50 m (165 ft).
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