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Inverter Air conditioning units require a certain RCD mcb Breaker type and rating electrical supply


Since the advent of Inverter heat pump air conditioning  there is the occasional problem  with electrical RCD breakers going out due to rating issues. Because inverter air conditioning units use a DC driven compressor there can be issues with the transfer from AC to DC which creates a lot of EMF thus causing the RCD mcb breaker to blow, the inverter board uses the Hertz supply going to the compressor to reduce or speed it up and for some reason low rated i.e 30mA RCD's have a rating problem.



The biggest problem with a underrated RCD breaker is that it can be a periodic issue, i.e the air conditioning units work for 2 months then all of a sudden a issue arises where the supply blows. The obvious first thought is that the inverter air conditioning unit itself has a major problem such as a PCB or compressor fault. This can waste valuable site time and customer down time while a fault is attempted to be rectified and on occasion parts being replaced.

The now obsolete but easier to electrically supply, fixed speed air conditioning systems used a direct on line motor compressor, either the compressor was Off or On according to the thermostat requirements. This made them a easer to rate electrically as they were a inductive rated load which usually meant using a C type breaker with no consequence to a RCD. The fixed speed models produced no high output  EMF because there were no inverter boards inside the outdoor unit with heavy electronic board based triacs and coils producing heavy electrical noise.


Which RCD Breaker Is Best To Use With Inverter Air Conditioning


It is best to use a (greater than) 100mA RCD breaker as this will give the electrical supply sufficient support to hold in while the air conditioning inverter system ramps up and slows down. Many electricians are unaware that air conditioning systems require a rating high than 30mA and it has to be said most of the time a 30Ma RCD will work. But if you are a electrician of air conditioning engineer with a issue with a RCD which keeps blowing it just might not be rated for the project.





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Orion Air Conditioning & Refrigeration Ltd, 10 Grisedale Court, Woburn Road Industrial Estate, Kempston, Bedfordshire, MK42 7EE, UK

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                               Last updated - 22/07/2018