Ramp testing a rcd

[alpha spark]

I've just got a new test kit and I've been having a fiddle with it it comes with rcd ramp test. Correct me if I'm wrong but does this basically test a rcd from 0ma to 30ma to see when the rcd trips if that makes sense it gradually increases to the point it takes the rcd out thanks

 

[Zeespark]

It does, if an RCD or RCBO is rated for 30mA, then it should trip within that current limit.

AndyGuinness

 

[alpha spark]

Yes that's great Andy cheers on what occasion would u use this. Would it just be done if u think u have a faulty rcd Rcbo etc

 

[NozSpark]

I always do a ramp test whenever I test a RCD, I also always do a 5x test even when it's not required!

But it can also be used as a diagnostic aid to help see how much standing leakage there is on appliances that are plugged in.

 

[alpha spark]

What do u mean 5 x test is not required all test sheets ask for x1 and x5

 

[Zeespark]

5x and x5 are the same thing Alpha.

AndyGuinness

 

[NozSpark]

TBH it's quite a while since I've had a look at what tests are required because for the time it takes I do them all, but from what I remember you don't have to carry out the 5x test is only required on socket circuits (might be wrong here though).

Just because there is a box on the test sheet does not mean that it is a required test.

 

[alpha spark]

I was under the impression a rcd test at x1 had to trip within 200 ms and on x5 it had to trip within 40ms on 30 ma

Just looked in OSG page 106 of green book if any ones interested them times I mentioned are for socket outlets to bs7288 the x5 is for additional protection I wasn't aware it wasn't required but have always done it don't suppose it hurts to do it as well as x1 as most test kits do auto rcd which do all 6 rcd tests x 0.5 x 1 and x5 ond both 0 and 180 degrees

 

[Technician]

Just to add; If BS RCD trip within 200mS if

BSEN RCD trip within 300mS at 1 times Ideltan.

 

[a1]

Isn't the case that the x5 test is NOT to be done on a 100ma RCD. (there's one example of when it is not required to be carried out).

 

[Technician]

That is how I saw it Admin; I also thought there were

no exceptions to the requirement for a test at five

times the setting of the device.

 

[Robin Spark]

Guys have a look at 415.1 Additional Protection: RCDs

415.1.1 The use of rcds with Idelta N not exceeding 30ma and an operating current of no more than 40ms at a residual current of *5 is recognised in ac systems as additional protection in the event of failure of the provision for basic protection and / or the provision for fault protection or carelessness by users.

Hence, it is only 30ma rcds (or lower) and not the higher rated ones eg 100ma 300ma rcds that you would need to test at *5.

 

[Andy™]

That is how I saw it Admin; I also thought there were no exceptions to the requirement for a test at five

times the setting of the device.

you dont test the higher rating RCDs at 5x because the fault current is too high

 

[Doc Hudson]

[quote name='Andy

 

[wallis.s.s]

The ramp test is handy to see if you rcd is working correctly and to see if you have any small background leaks to earth that would lead to nuisance tripping but you should pick them up on your IR tests

 

[Manator]

Ramp testing just as the Doc has said is a valuable test when a nuicance tripping RCD is over sensitive, 30mA RCD,s will normally ramp at around 27mA anything lower than 3/4's of the value could be suspect. x5 tests should not be carried out on any high value RCD, the fault currents passed through are too high, and should only ever be done (if required) under total controlled conditions.

 

[Guy]

Why does the positve side and the negative side (0'-180') of the sine wave have to be measured please?

 

[Zeespark]

Because you have to measure both sides of the RCD for the AC sinewave. MK RCD's are measured on the negative, where I do believe others are measured on the positive side.

AndyGuinness

 

[Guy]

Because you have to measure both sides of the RCD for the AC sinewave. MK RCD's are measured on the negative, where I do believe others are measured on the positive side.AndyGuinness

Thanks, but still dont get it, I am unsure why a line/neutral imbalance is effected by pos/neg................im now off to use my subscription

 

[johninlondon1]

Because AC current is 50hz (thats back and forwards 50 times a second, if you test it for 40 milli seconds you wont have tested through the full 50 Hertz, I think