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Testing And Tagging Dimmers With Rcbo


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#1 Don Allen

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Posted 10 September 2018 - 12:46 AM

Is there an instruction on testing and tagging dimmers such as the GenVI dimmer as the supply voltage of 415V requires an insulation test of 1000V which would be detrimental to the RCBO ?

 

Thanks

Don


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#2 Greg Hughes

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Posted 10 September 2018 - 07:42 PM

The supply is not 415v - the supply is generally three phases of 230-240 volt, but it can also be single phase supply. The dimmer only functions on 240v and the Neutral must be adequate for the nature of the work done ( ie phase controlled dimming)

The RCBO's are tested from the load side, not the mains supply side and each RCBO is a 240v device. The Lena RCBO's that LSC have used for about 4 years now have been approved for use by Energy Safe Victoria https://www.esv.vic....omplaint-rcbos/https://www.esv.vic....omplaint-rcbos/

One thing I will mention is that you cannot megger the actual supply phases to any dimmer (unless they are isolated) as that may damage the dimmers electronics. 


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#3 Greg Hughes

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Posted 10 September 2018 - 09:27 PM

From the info at hand, you can test  the Earth Continuity from the earth pin on the supply plug to all earthing points (including Chassis), and you can also test insulation of the supply cable (when it is isolated from the dimmers electronics). RCBO testing is done via a Trip Tester to each Outlet and must be performed when the dimmer channel is driven to 100%. I hope that helps.


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#4 Don Allen

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Posted 12 September 2018 - 07:23 PM

For the three phase supply cable, the voltage between the phase conductors is 415V AC and as the Insulation Resistance test is done at twice the working voltage, PAT testers use 1000V DC to test the insulation.

 

A lot of PAT testers use 500V DC to test insulation for single phase 230-240V AC appliances to meet the original requirement of testing at twice the rated voltage. They connect active and neutral in parallel so when they test insulation resistance to ground, there is no potential difference applied between active and neutral, so no damage occurs to the equipment under test. Some older testers and most new one have the option to use 250V DC if you are aware of surge protection devices, such as MOVs/EMI filtering or protective earth detection.


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#5 Greg Hughes

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Posted 13 September 2018 - 03:30 AM

As already stated, you are fine to test the three phase supply cable (for insulation) at any voltage as long as it's isolated from the dimmers electronics.

However, every dimmer has specific electronics connected to the mains (each manufacturer has differences) and therefore some care is needed. Shoving 1000 volts into any dimmer from the supply side will more than likely cause damage. Also your original post mentioned 415 volts and RCBO's. Each RCBO protects an output from the dimmer at 240v  - not the incoming supply. So as per my post above, (1) test earth continuity,(2) test the incoming mains cable (isolated) for insulation issues, and (3) test any 240 volt RCBO as you would test any RCBO.

I make mention of the fact that dimmers do not utilise 415 volts simply because of the number of electricians I have come across who simply do not know that. They see three phase cable and assume it is a 415v system (no Dimmer I know of runs at 415v). 


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