SIQuench: Arc fault protection beyond the standards

Siemens SIQuench arc quenching device

The occurrence of an internal arc fault in a well-designed, type-tested, correctly installed and operated switchgear is improbable – but not impossible – mostly linked to human-related errors or environmental causes. The safety risk is only one aspect of arc faults. The damage to equipment causing power supply and process disturbance may lead to substantial costs, in the order of millions of euros per incident. In the case of occupational incidents, the total costs may be even higher due to medical and legal expenses. Said catastrophic effects could be mitigated through acting on the arc itself by limiting its duration.

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SIQuench - your natural choice!

The solution

SIQuench is an active arc effect mitigating system by Siemens, quenching the internal arc in sub-cycle times. It dramatically reduces pressure and avoids thermal, contamination and toxicity effects which are damaging the equipment with its surroundings. In the event of an internal arc fault it minimizes the duration of downtime for operations resulting in drastically reduced economic losses.

How does it work?

The system works in conjunction with an arc protection relay to rapidly and

reliably detect the ignition of an internal arc via continuous monitoring of light

and overcurrent – the standard characteristics of an arc that make it detectable.

 

Upon detection of an internal arc, the arc protection relay simultaneously

sends a trip signal to the main circuit-breaker and a trigger signal to the

controller of the SIQuench.

 

The enhanced arc effects mitigation functionality provided by SIQuench is achieved

by consciously and rapidly closing the main current path of the switchgear to earth

via dedicated phase-wise primary switching devices – creating a lower-impedance

current path to the fault current – and transforming the open arc into a controlled

3-phase metallic short circuit. Continuous self-supervision maximizes the reliability

of the system.

 

 

Condition of a 12 kV NXAIR cable compartment after an internal arcing test with a fault current of 80 kA (peak) / 31.5 kA (r.m.s.), with arc ignition inside the cable compartment

Your benefits at a glance

The value received

The system works in conjunction with an arc protection relay to rapidly and reliably detect the ignition of an internal arc via continuous monitoring of light and overcurrent – the standard characteristics of an arc that make it detectable.

Continuous self-supervision maximizes the reliability of the system.

Capability

It is capable of extinguishing the arc fault in less than 5 ms* – long before the pressure peak, and before the arc can cause any significant damage. SIQuench is reusable up to its permissible switching duties:

 

• Capable of switching 5 times at the full rated short-time withstand current (with peak withstand current)

• Capable of switching 30 times without load for testing / commissioning purposes

 

*  From arc ignition to closing of the quenching device

Upon detection of an internal arc, the arc protection relay simultaneously sends a trip signal to the main circuit-breaker and a trigger signal to the controller of the SIQuench.

The enhanced arc effects mitigation functionality provided by SIQuench is achieved by consciously and rapidly closing the main current path of the switchgear to earth via dedicated phase-wise primary switching devices – creating a lower-impedance current path to the fault current – and transforming the open arc into a controlled 3-phase metallic short circuit. Final clearance of the dead short circuit provided by the SIQuench is done by tripping the main circuit-breaker.

Availability

The damage to the switchgear is limited to an insignificant level and wholly avoided for the direct surroundings. This leads to an extreme reduction of repair costs along with absolute elimination of switchgear room and surroundings cleaning costs.

 

The switchgear can be restored back to operation within minimum maintenance time, meaning an incredible boost in system and process availability.
The system needs no replacement after an arc fault.

SIQuench is maintenance-free for 20 years and capable of serving for 30 years with maintenance at the end of the given maintenance-free period.

Installation

SIQuench is available as a complete solution integrated into type-tested, internal arc classified, medium-voltage switchgear type NXAIR, rated up to 17.5 kV, 50 kA, 4000 A.

 

There are two versions available for the point of installation:

 

  1. In busbar compartment of NXAIR, fixed-mounted
  2. In switching-device compartment of NXAIR, withdrawable