MCCB TERM

 Iu

 Rated uninterrupted current (Iu) The rated uninterrupted current of an equipment is a value of current, stated by the manufacturer, which the equipment can carry in uninterrupted duty.

KA rating

kA rating of an MCB or an MCCB is the maximum current it can safely interrupt in case of a short circuit. If the current goes beyond this value, the circuit breaker could be damaged. kA rating is known as the short circuit withstand capacity or ultimate breaking capacity of a circuit breaker

Icu

unlimited break Capacity of the circuit breaker Which means the circuit breaker can break the maximum fault current without damage. Typically for MCB the maximum Icu will be 6KA to 10 KA for MCCB Icu may be 200kAmps.

Ice

Ics is the amount of current that the circuit breaker can safely withstand without being damaged for example 6 kA or 6000 A and remain usable. Icn is the amount of current the circuit-breaker can safely handle but would not remain usable.

Ue

Rated working voltage (Ue) is the continuous operation voltage for which the MCCB is designed. This value is typically equivalent or close to a standard system voltage. Operating short-circuit breaking capacity (Ics) is the highest fault current that the MCCB can trip without being damaged permanently.

Ui

Rated insulation voltage (Ui)

This is the value of voltage to which the dielectric tests voltage (generally greater than 2 Ui) and creepage distances are referred to. The maximum value of rated operational voltage must never exceed that of the rated insulation voltage,

Uimp

Rated impulse-withstand voltage (Uimp)

This characteristic expresses, in kV peak (of a prescribed form and polarity) the value of voltage which the equipment is capable of withstanding without failure, under test conditions. Generally, for industrial circuit-breakers, Uimp = 8 kV and for domestic types, Uimp = 6 kV.

MCB data

 

• Product Modal No
• Max Current Rating
  (6, 10, 16, 20, 25, 32, 40, 60, 63 etc)
• Operation Symbol
• Breaking Capacity Type
• Breaking Capacity (Max Short Circuit Current)
• Operating Voltage(230V, 400V, 440V)
• Tripping Curve Type
• Energy Class
• ON-OFF Indication
• Catalog No

• Product Modal No
• All reputed manufacturer has a particular code of each device type. It will be very easy to communicate with seller or manufacturer, if you quote the model no., in case of any service complaint.
• Max Current Rating
  (6, 10, 16, 20, 25, 32, 40, 60, 63 etc)
• As shown in example, it is mentioned C20 (and in the below image, it is B25). First letter is showing the characteristics curve. There are three characteristics curves (In common use) available- B C & D. B curve indicates that short circuit rating of device is in range of 3-5 times of standard rated current (Which means, TIME for Trip initiation i.e. the less rating of the the time will be Fast acting, like for protecting sensitive Electronics devices and equipment). C curve indicates it to be 5-10 times and D curve indicates it to be 10-20 times. Be very careful while selecting this. On a resistive load (say heater, normal lighting load) it will B Curve, for inductive load (Like pump, Motors etc.) it will be C curve and for highly inductive or capacitive load it will be D curve. The numeral part indicates rating of MCB in Ampere. In the given example it is 20A. MCB rating is very important and be very precise about it.
• Operation Symbol
• It is in Volts and is the operational voltage for which current rating is said. In three phase it is usually 400V or 415 V. For single phase it is 230V or 240V. Choose as per your application only.
• Breaking Capacity Type
• 
  
• Breaking Capacity (Max Short Circuit Current)
• Breaking capacity can be defined as the maximum level of fault current which can be safely cleared. It is written as in numerals like in in example it is 10000. It means it 10000A = 10kA. Choose breaking capacity as per your fault level possible. Since it is the parameter which may increase or decrease the cost, so it should be properly decided. Breaking capacity should be higher than the possible fault level. For domestic application where fault level cannot be calculated easily, it advisable that go for a standard breaking capacity of 10kA which is easily available. Please note that this rating is mentioned as per testing made on basis of IS 60898. If it is for IEC60947-2 then it need to be mentioned separately.
•  Voltage(230V, 400V, 440V)
•  It is in Volts and is the operational voltage for which current rating is said. In three phase it is usually 400V or 415 V. For single phase it is 230V or 240V. Choose as per your application only.
• Tripping Curve Type
• Energy Class
• MCB normally work on current limiting feature. It means that it does not allow fault to get it’s peak and trip before that. But since there is some time consumed in tripping, fault current will create some energy which will exist in system. This energy is termed as let through energy. For efficient MCB operation it should be limited. On basis of amount of energy it is classified in class 1, class 2 and class 3. Here Class 3 is best which allows maximum 1.5L joule/second. This is being tested as per IS 60898.
• ON-OFF Indication
• It shows the ON-Off Indication while in operation. Never buy an MCB which don’t have clear status indicator because serious damage may be occurred with ON-OFF confusion of the device.
• Catalog No
• Most of the MCB manufactures put the catalog number of the MCB products. This code provide the overall information on the manufacture website such as MCB specification and Datasheet ect.