To meet the increasing safety demands of people, electrical equipment manufacturers have launched many civil electrical network protection devices to ensure maximum safety for users, the most typical and popular are MCB (Miniature Circuit Breaker) and MCCB (Molded Case Circuit Breaker), RCD (residual current device), fuse…
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Contents
How to choose MCB, MCCB, Contactor, Wire for motor control cabinet
In industry, most motor controls use a motor control cabinet. Depending on the needs, there are different types of motor controls:
- Direct Start Star or Delta
- Inverter Start
- Soft Start
Either way, some devices need to be carefully calculated in terms of technical parameters such as MCB or MCCB, Contactor, Thermal Relay, Wire. These are the basic components for the Electrical Cabinet.
How to calculate, choose suitable MCB or MCCB?
We apply the classic formula: P (3Phase) = (3rd Root) x Ud x Id x CosF
Assume Pdm = 5.5kw, CosF = 0.8
We calculate Id = 10.5 A
From here we choose the current for MCB, in fact when choosing MCB for protection we choose Icb = (1.5 or 2) x I d. So with I = 10.5A we choose Icb = 20A.
Depending on the actual calculated Ampere level we choose MCB or MCCB accordingly
From the calculated I value we choose Contactor. I = 10.5A then we choose Contactor with range A of 18A (choose surplus). Choose thermal relay 12A-18A
Select wires for the electrical cabinet
From the calculated I is 10.5A, we choose the appropriate wire. In fact, to choose the wire, people calculate the level of 1mm2 equivalent to 3-5A, from there choose up. With the calculated level of 10.5 A, we can choose the appropriate wire 2.5mm2 wire or more carefully choose 4mm2. Depending on the coefficient of demand (k) of the operating load, choose the appropriate wire.
