NSE AG

NSE AG
Bremgarterstrasse 54
CH-5610 Wohlen

Tel:0041 (0)56 618 77 99
Fax:0041 (0)56 618 77 90
E-Mail: info@nse.ch
Internet: www.nse.ch

DIGIMUT

Digital replacement for primary relays

Description
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Encapsulated medium-voltage systems with circuit breakers (on a carriage or permanently installed) have a life span of 40-45 years, while the primary protection relays that are frequently installed on such power circuit breakers have a life span of around 20 years. These relays are now technically outdated, frequently so old that they are no longer precise and carry an increased risk of total failure leading to unselective deactivation, damage to the network and even personal injuries.

Such primary protection relays need to be replaced in the near future to prevent these systems from losing value, although the circuit breakers themselves will remain functional for a long time. Instead of replacing the entire installation the DIGIMUT system merely replaces the primary relays with DIGISAVE RN digital protection relays. This involves installing three structurally similar AKP current transformers in place of the primary relays. The DIGISAVE RN protection relay is installed together with the trigger mechanism for the power circuit breaker in a secondary box that is mounted on the circuit breaker. Only the front doors of the existing installation are replaced.

The DIGIMUT system fits on all the usual power circuit breakers and sustainably increases the security of operations and supply for the existing installation. Compared to an entirely new system it represents a cost saving of over 70%!

Special features
  • Removal of outdated and dangerous primary protection relays
  • AKP current transformers facilitate fault recognition even in the sealed ends
  • There is no need to install triggering coils in the power circuit breakers
  • Existing mechanical triggers are used
  • Stiffening plates can be retrofitted at the switch for increased security
  • Cell door converted to a closed front (for arc flash safety in the event of a busbar fault)
  • Safe to operate because converters and cutouts can be tested and maintained safely and easily with the switch in its extended position.
  • Permanent revision, thanks to the low conversion costs, brief downtime and high level of re-use of existing investment
Applications
Disassembly
  • Replace primary relays with identically constructed AKP current converters
  • Install secondary boxes on existing power circuit breakers
  • Numerical protection relay DIGISAVE RN with extensive functionality and current transformer power supply
  • Simple, extremely fast trigger mechanism for switch control (integrated into the secondary box)
  • Optional use of voltage transformers and directional protection relay DIGISAVE RD
Conversion
  • On-site or at NSE's workshop
  • Carried out entirely by NSE installers or independently by properly instructed power company personnel
Utilisation
  • Power circuit breaker of type HPTW(Z) 306/506 / HVTW406
  • Power circuit breaker of type SR612 / SR624, on a carriage or to plug-in

Downloads

Technical drawings are available in the LOGIN-area.