Questions tagged [rcd]

Residual current device (RCD), residual-current Circuit breaker (RCCB), ground fault circuit interrupter (GFCI), ground fault interrupter (GFI) or an appliance leakage current interrupter (ALCI). The exact wording of the term varies from country to country.

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Do RCDs work for DC systems?

I'm designing a product powered by an alternator with a DC regulator that will provide me with 24 V DC and something like 100 A rated consumption. Do RCDs protects against earth leakage current in DC ...
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58 views

Will RCDs function properly in the Philippines?

In the Philippines the two pin plug can go into power socket either way. Most domestic wirings have an earth at the power pole. My question is can an RCD be installed and function 100 % in ...
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119 views

How do RCD Testers work?

RCD-Testers can be used to check if the residual current device (RCD) of the installation is properly working. How to they do this? I want to build my own RCD-tester. Which circuit can be used to ...
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2answers
317 views

Why so many specs for RCD vs US GFCI (or RCDs?)

Why are there so many RCD (Residual Current Device) specs and mA tripping thresholds for use in equipments in Europe vs the USA where they were not used (but only 5mA GFCI for personal safety)? Don't ...
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351 views

Using a residual current device when there is an isolation transformer

In a system, currently there is no circuit breaker and RCD, but there is an isolation transformer as in the diagram below: simulate this circuit – Schematic created using CircuitLab As you see ...
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2answers
101 views

RCD tripped when measuring with a scope

Below was my setup: The moment I connected the probe the RCD tripped. My scope was earth grounded. Does that mean I shorted the neutral and the earth ground? I know that neutral and earth are ...
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2answers
187 views

Automatic Self-Test Circuit in GFCI outlet

What kind of self-test circuits or method do they used in the GFCI outlets generally? Is it just firmware or is there a physical addition (and what it is usually?) This is because after 2015, it is ...
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1answer
78 views

Basic 3 phase question

I've come across this question at work and it has stumped me... even though it is quite basic. A distribution board is supplied by 3 phase 415 AC power. From the distribution board to a circuit ...
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3answers
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How do I protect myself when testing a PCB that involves an AC line?

I have to test prototype PCBs that convert household AC into several DC voltage levels. I concern about my safety when working with AC and would like to know how to properly setup a testbench that, ...
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4answers
222 views

Why do RCDs / GFCIs sense differentially rather than directly?

As far as I know, all RCDs / GFCIs sense leakage current by differential measurement between active and neutral with a current transformer. Both the active and neutral wires will pass through the ...
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189 views

Confusion with RCD principle of operation

I understand that an RCD is a device that interrupts an ac circuit (usually in outlets) if current between live and neutral/ground is not the same, indicating something is wrong with the circuit. It ...
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2answers
110 views

Transformer Question - Two Output of Different Voltage

I'm fairly new to electronics, but still have a basic understanding (1st year Electrical Engineering Student). I've started a project of repurposing a used treadmill I found online for $20 as a ...
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88 views

Residual-current device: Would a big coil trigger it because it stores electrons? [closed]

Imagine a residual-current device at your home - basically it counts influx of electrons vs outflux of electrons. If there is a missmatch (e.g. I=30mA over t=30ms), it triggers and disables the ...
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415 views

How to wire a RCBO/GFCI correctly (in series with the upstream RCBO/GFCI)?

For one of my projects, I need to add a RCBO/GFCI for the protection of the users. I know that there is a RCBO somewhere up the chain, therefore I am facing a confusion: there is a non-zero resistance ...
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2answers
152 views

How does a GFCI breaker protect me if my device has no connection to ground? [closed]

I use a hairdryer with a 2-prong US plug (no ground). Suppose I plug it into a GFCI-protected outlet and drop it into a sink full of water. Will the GFCI still trip even though my hairdryer doesn't ...