© ABB Group July 6, 2011 | Slide 1

by NS Koh

ABB Pte. Ltd.

SS & IEC Requirements for MCB & RCCB

By NS Koh

Since the withdrawal of SS 359 on 30th Jan 2004, International Standard IEC 60898 was adopted for MCB.

IEC 60898 : Circuit-breaker for overcurrent protection for household and similar installation

Scope : AC air-break circuit-breakers 50Hz or 60HzUn < 440VIn < 125AIcn < 25kA

Designed for use by uninstructed people and for not being maintained

SS & IEC Requirement for MCB & RCCBMCB

Overcurrent protection

Overload protectionProtection of cables and wires aswell as system parts againstexcessive heating up duringoperating overload in a fault-freecircuit by delayed switch-off

Short-circuit protectionProtection of cables and wires aswell as system parts against theeffects of a dead short-circuitbetween conductors with adifferent potential by current-limiting switch-off

Protection of cables and wires in case of overcurrent

Thermal Tripping Magnetic Tripping

SS & IEC Requirement for MCB & RCCBMCB

SS & IEC Requirement for MCB & RCCBMCB Tripping Characteristics

IEC 60898 Termal Release Trip time Electromagnetic Release Trip time

Type Non-trip Trip Hour Hold Trip sec

B 1.13 In > 1 3 In > 0.1

1.45 In < 1 5 In < 0.1

C 1.13 In > 1 5 In > 0.1

1.45 In < 1 10 In < 0.1

D 1.13 In > 1 10 In > 0.1

1.45 In < 1 20 In < 0.1

SS & IEC Requirement for MCB & RCCBMCB Tripping Characteristics

0.5 ms after short-circuit current is released

Miniature Circuit BreakersTripping of an MCB

0.5 ms

1 ms after short-circuit current is released

Miniature Circuit BreakersTripping of an MCB

1 ms

1.5 ms after short-circuit current is released

Miniature Circuit BreakersTripping of an MCB

1.5 ms

2 ms after short-circuit current is released

Miniature Circuit BreakersTripping of an MCB

2 ms

2.5 ms after short-circuit current is released

Miniature Circuit BreakersTripping of an MCB

2.5 ms

3 ms after short-circuit current is released

Miniature Circuit BreakersTripping of an MCB

3 ms

SS & IEC Requirement for MCB & RCCBMaximum disconnection times: TN-S System

3ms

SS & IEC Requirement for MCB & RCCBRCCB

SS97 is a modified adoption of International Standard IEC 61008-1

SS97 & IEC 61008-1: Residual current operated circuit-breakers without integral overcurrent protection for household and similar uses (RCCBs)

Scope : Functionally Dependent of or Independent on line voltage Un < 440VIn < 125A

Protect person against indirect contact and fire hazards due to earth persistent fault

SS & IEC Requirement for MCB & RCCBRCCB

Major difference between SS97 and IEC 61008-1 is the tripping time:

General Type Max Break Times (s)

Standard Category 1 x I n 2 x I n 5 x I n 10 x I n, to 500A

IEC 61008 n < 30mA 0.3 0.15 0.04 0.04

SS 97 n< 30mA 0.1 0.1 0.04 0.04