Newsletter from Emcomp International AB Web version
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Usage of a AC circuit breaker on a DC voltage?

This is common practice and the general explanation used in most cases to explain the fact is “we use what we have” or “it has always been done this way”. For low voltage DC applications, such as 12 or 24 VDC, this may be OK, but is it right?

Let us point out two things:

  1. What will your customer think when they look at the system you have built and the circuit breakers protecting their system is marked with AC voltage values and symbols.    
  2. There is a significant difference in switching an AC versus a DC voltage. When a circuit breaker trips, an arc is created. In an AC circuit, the extinguishing of the arc is aided by the zero crossing of the voltage waveform. However, in a DC system the circuit breaker does not get this assistance since the voltage is a fixed value. If the circuit breaker cannot self-extinguish the arc, the arc is sustained resulting in a dangerous situation. CBI as a producer always distinguish between AC and DC products. This has forced them to push the boundaries and the result is the new developed range for high DC voltages. The Y-frame. It works with the same proven Hydraulic-Magnetic principle as the other ranges. I.e. no need to de-rate the circuit breaker due to high ambient temperatures. 

The 300 VDC Y-frame utilises a permanent magnet to aid in extinguishing the arc. For applications where a non-polarized (reverse feedable) product is required, a 150 VDC single pole version is available. In a similar manner to the polarised version a 2 pole series connected product can provide a 300 VDC module. It is then 2x13mm wide.
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The CBI Y-frame

The Y-frame perfectly addresses the trend for power distributions to use high DC voltages such as 400 VDC, moving away from the traditional AC or low voltage DC applications. This helps in increasing the power throughput without drastically increasing system or conductor sizes.

In traditional DC-systems where 12/24/48 VDC have previously been used, power throughput has been limited without substantial investment. It is now possible to reduce the copper used in a system by using higher DC voltages and therefore providing a considerable cost saving in current products with increased performance.

Until now, there has not been any suitable MCB’s for higher DC voltages. Now there is! Contact us for more information!
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Other solutions
The temperature independent circuit breakers manufactured by CBI is the heart in our offering. We at Emcomp can assist you with sub assemblies, custom made harness, mounting hardware etc, or maybe just quick and efficient service with a smile.
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