DIN MCB

Based on the specifics of the device or installation site, the following factors are needed to be considered during the selection of an MCB.

• The tripping or overcurrent characteristics, typically known as their ‘trip curve’  
• The breaking capacity which is the maximum current a Miniature Circuit Breaker can interrupt without causing damage or releasing an arc. This rating should ideally match the strength of any surges that might occur in the area of installation. The standard measurement of breaking capacity is kiloamperes (kA) 
• The number of trippable units or poles 

IPD offers ABB’s System pro M compact® Miniature Circuit Breakers (MCBs) in three tripping characteristics namely C, D and K to cater domestic, industrial and commercial applications.

Type C
Detects and trips the circuit on sinusoidal residual current and on residual pulsating or continuous direct current of either polarity, with moderate inrush currents, suitable for three phase and single phase applications with electronic components.
They are designed to trip at currents between five and ten times their rated load. Well suited for commercial and industrial purposes and these MCBs are usually used for high inductive loads where switching surges are high such as in fluorescent lighting and small motors.

Type D
Detects and trips the circuit on sinusoidal residual current and on residual pulsating or continuous direct current of either polarity, with high inrush currents, suitable for three phase and single phase applications with electronic components.
D type MCBs are the least sensitive type, only activating when current surges to between ten and twenty times the recommended maximum. Used for extremely high inductive loads such as motor with high inrush current, Some frequent examples of the application of these devices are found in x-ray machines, UPS systems, large winding motors, and industrial welding equipment.

Type K
Detects and trips the circuit on sinusoidal residual current and on residual pulsating or continuous direct current of either polarity, with high inrush currents and solves the conflict of service continuity in the event of peak currents and rapid disconnection in the event of a short-circuit when compared to C and D. It is used in three phase with electronic components. They are ideally suitable for motors.

Miniature Circuit Breakers (MCBs) have a general function of protecting electrical installations against faults such as overloads and short circuits, whereas Residual Current Devices (RCDs) are especially built in order to provide protection against the frequently fatal risk of electrocution from touching exposed wires or incorrectly earthed cables. Their operation is precisely within electrical circuits to detect faults and disrupt potentially lethal currents.

They are also known as ground fault circuit interrupters (GFCIs).

In theory, any component that is compatible with a particular device in terms of technical specifications can be used. Nevertheless, mixing brands within the same installation is not recommended as it makes testing less consistent and can invalidate warranties and installation guarantees.

The System pro M compact® MCB’s are IP20 finger safe, which is the ultimate standard of touch protection, equipped with 35 mm² + 10 mm² cylinder lift twin terminals, a well-established and trustworthy technology. It is designed for refined and sophisticated industrial use. The cross wiring can easily be done by inserting the System pro M compact® busbars into the rear terminal part and then the incoming wires into the front part of the terminal.

These certified Miniature Circuit Breakers are intended for indoor use, and under pollution and humidity-free conditions like in households or similar installations where overcurrent protection will not likely be maintained by unskilled users. Alternatively, it can be described as applications in which the final distribution electrical switchboards of buildings in which the nominal current does not exceed 125A.

IEC 60947-2 governs circuit breakers (CBs) for industrial applications. They protect electrical power distribution of up to 1000 volts AC and 1500 volts DC with an entire spectrum of rated currents from 0.5 to 6300A. Often used in utilities and manufacturing facilities.

IPD offers ABB’s RCBO (Residual Current Circuit Breaker with over-current protection) switch, a range designed to ensure flexibility with uncompromising safety and are compliant to worldwide product standards (AS/NZS 61009-1 Ann. G; AS/NZS 61009-2-1), warranting reliability and safety for people and assets. This standard applies to residual current operated circuit breakers with integral overcurrent protection functionally independent of, or functionally dependent on, line voltage for household and similar uses, for rated voltages not exceeding 440V AC with rated frequencies of 50Hz, 60Hz or 50/60Hz and rated currents not exceeding 125A and rated short circuit capacities not exceeding 25kA for operation at 50Hz or 60Hz.

The RCCB has a very comparable functionality to the RCBO. However, it doesn’t deliver integral overcurrent protection and so doesn’t protect against overloading or short-circuiting. Instead, the RCCB provides exclusive earth leakage protection and necessitates the fitting of an external circuit breaker for the assurance of overload and short circuit protection.

Type AC
A type AC RCCB (Residual Current Circuit Breaker) detects and trips the circuit on sinusoidal residual current and can be used in applications where resistive, capacitive and inductive loads are present, generally without any electronic components.

Type A
A type A RCCB (Residual Current Circuit Breaker) detects and trips the circuit on sinusoidal residual current and on residual pulsating or continuous direct current of either polarity up to 6mA and can be used in three phase and single phase applications with electronic components.

Type B
A type B RCCB (Residual Current Circuit Breaker) detects and trips the circuit on sinusoidal residual current up to 1kHz, on residual pulsating or continuous direct current of either polarity and in addition for composite residual currents. It is used in three phase and single phase applications, well suited for usage along with electronic equipment and Power Electronic Converter Systems (PECS).

Type AP-R
A type AP-R RCCB (Residual Current Circuit Breaker) detects and trips the circuit on sinusoidal residual current and on residual pulsating or continuous direct current of either polarity up to 6mA along with resistance to unwanted tripping, offering good protection and isolation. It is used in three phase and single phase applications with electronic components.

IPD offers ABB’s Residual Current Circuit Breaker (RCCB), a range designed to ensure efficiency and protection and are compliant to worldwide product standards (AS/NZS 61008-1; IEC/EN 61008-2-1). This Standard proposes necessary safety and associated requirements for residual current operated circuit breakers for household and similar uses, not integrating overcurrent protection, for rated voltages not exceeding 440V AC and rated currents not exceeding 125A, intended mainly for protection against shock-hazard.

The IEC publication 60479-1” Basic safety publication on the effects of current on human beings and livestock” provides basic guidance on the effects of shock current on human beings and livestock, for use in the establishment of electrical safety requirements. The threat to a person depends mainly on the magnitude and duration of the current flow for a given current path through the human body.

PWhen a current higher than 30 mA passes through a part of a human body, there is serious danger for people if the current is not interrupted in a very short time.

It’s a general assertion that in order to safeguard people from direct contact a highly sensitive Residual Current Device (RCD) is strictly recommended. According to IEC publication 60364-4-41 (Low-voltage electrical installations – Part 4-41: Protection for safety – Protection against electric shock) a residual Current Device (RCD) suitable for protection against direct contact needs to have its trip threshold set at 30 mA for AC current. These devices, used to disconnect the power supply automatically, operate as fast to prevent injury to, or death by electrocution, of a normally healthy human. In fact, it detects any earth leakage current which may circulate through a person, and which does not loop back to the source via the live conductors.

It is referred as a direct contact when a person comes into contact with conductors that are usually live. The major protection against direct contacts is the physical prevention of contact with live parts by means of barriers, insulation, inaccessibility, etc.

An indirect contact refers to a person coming into contact with an exposed conductive part which is not normally alive but has come to be alive accidentally due to failed insulation, etc. The protection against indirect contacts is mainly realized by disconnection of the supply, by means of a residual current device. A Residual Current Device (RCD) of high sensitivity (IΔn ≤ 30mA) are able to provide both protection against indirect contact hazards and the additional protection against the dangers of direct contact.

Typically, a Residual Current Device (RCD) turns off the power between 10 to 30 milliseconds (ms).

This varies based on the number of circuits or fuses there are on a given switchboard or fuse box. As no more than 3 circuits or fuses are permitted per Residual Current Device (RCD) it may be necessary to install multiple Residual Current Device (RCD) switches to larger fuse boxes. In any given instance a minimum of two residual current devices (RCDs) are required.

Yes, it is now legislated that all new installations have RCDs (residual current devices) protecting all circuits. If a switchboard is upgraded, it will need to have RCDs (residual current devices) put across all circuits.

IPD offers ABB’s Residual Current Device (RCD) switch, a range designed to ensure flexibility with uncompromising safety and are compliant to worldwide product standards (AS/NZS 61009-1 Ann. G; AS/NZS 61009-2-1, IEC/EN 62423), warranting reliability and safety for people and assets. This standard applies to to residual current operated circuit breakers with integral overcurrent protection functionally independent of, or functionally dependent on, line voltage for household and similar uses, for rated voltages not exceeding 440 V AC with rated frequencies of 50 Hz, 60 Hz or 50/60 Hz and rated currents not exceeding 125 A and rated short circuit capacities not exceeding 25 kA for operation at 50 Hz or 60 Hz.

The Residual Current Device (RCD) switch comprises of RCD block DDA200 and an RCD relay RD2. RCD relay operates with an external toroid transformer type TR with window diameter ranging from 29mm to 210mm, which is sold separately.

IPD offers ABB’s SHD200 and E200 switch disconnectors for safe switching compliant to AS/NZS 60947- 3 standards. This standard applies to switches, disconnectors, switch-disconnectors, and fuse-combination units to be used in distribution circuits and motor circuits of which the rated voltage does not surpass 1000V AC or 1500V DC. The manufacturer stipulates the type, ratings, and characteristics according to the relevant standard of any incorporated fuses. Identical to and reproduced from IEC 60947-3.