Page 103 - E24 Electrical Notebook

LV MCCB Switch / Panel / Distribution Boards - 99

Leading Safety Technology

Every day Compromise:

Personnel & Property Protection vs. Selective Trip Settings
• High set or non-instantaneous circuit breakers sacrifice people &

property protection for selective coordination
• Current limiting molded case circuit breakers are quick to respond &

provide excellent protection, but are challenging to coordinate for
selectivity
• Maintenance switches sacrifice coordination for protection

Your power distribution system can be selective without sacrificing arc
flash protection. ArcWatchTM = A balanced solution

ArcWatchTM is powered by Instantaneous Zone Selective Interlocking (I-ZSI) and
Wave Form Recognition (WFR).

I-ZSI allows intelligent communication between circuit breakers like traditional System Reliability System Protection
ZSI, but adds interlocking of the INST protections of the trip units. This allows
more sensitive and fast-acting circuit breakers to be selective when responding Selective Arc Flash
to a fault. Each circuit breaker will only operate when needed and act as back Coordination Mitigation
up only when necessary.

GE’s I-ZSI capability provides the fastest interlocked protection in the industry.
You can get instantaneous protection, selectively, regardless of the size of your
system or main circuit breaker.

WFR provides current limiting devices the intelligence to recognize the operation GE
of downstream devices. An Instantaneous algorithm allows a feeder circuit
breaker to be set very sensitive and still provide selectivity while providing
instantaneous protection where you need it. What's more, the setting is not
dependent on a complex coordination study; it simply depends on the device with
which you are trying to be selective. When paired with GE current limiting molded
case circuit breakers, WFR allows lower INST pick-up settings while maintaining
full selective coordination.

Only GE’s ArcWatchTM solution provides arc flash protection and instantaneous selective coordination – simultaneously!

With
Short-Time &
Instantaneous
ZSI Enabled:
Selective
to 85kA

Curve
Overlap
Shows
Selectivity
Limit

Curve Maximum Instantaneous Selectivity that May be
Overlap Achieved Using I-ZSI Limited Only by the Short
Shows Circuit Rating of the Downstream and Withstand
Selectivity Rating of Upstream Device.
Limit

Normal Operations: Sensitive Response; Short-Time Protection Limits Selectivity to less than 6kA

As the curve overlap illustrates (see lower right diagram), zone selective interlocking (ZSI) is effective, but has
limitations. With no ZSI, selectivity is limited to <6kA. With ZSI, it improves to >10kA. With Instantaneous Zone
Selective Interlocking (I-ZSI), shown in the upper right diagram, 85kA selectivity is achieved and instantaneous
protection still provides reduced arc flash energy to maximize both system reliability and protection.

GE Industrial Solutions Tel : 0800 587 1251

3 Oakland Road Fax : 0800 587 1239

Leicester

Leicestershire

LE2 6AN Website : www.ge.com/uk/industrialsolutions