350ma test for type A rcds

[sinewove]

Just wondered how we would know a 30ma type A rcd/rcbo will trip at 30ma,if we
can only test it at 350ma?Think I must be missing something.Thanks for any help.
Regards,S

 

[nicebutdim]

Sorry thought they were tested at 350ma?

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

Why would age be a factor? 30mA is 30mA, just as it was 100 years ago.

Are they 30mA or 300mA RCDs?

What is their part number?

What trip current is indicated on the front? Perhaps 0.3A

 

[timhoward]

Sorry thought they were tested at 350ma?

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

This could easily get confusing....

Before amendment 2 they were tested at X 1/2, X1 and X5
So a 30ma RCD would be tested at 15ma, 30ma and 150ma.
They were also tested on a rising and falling wave pattern (0 degrees and 180 degrees)
The pass results were no trip at 1/2, 300ms at x1 and 40ms at x5

(I had assumed you were talking about 350ms, hence my units comment, but let's forget that.)

Since amendment 2 the minimum testing is reduced to testing at x1, so just 30ma.

Now your 2nd comment about brand new Hager Type A's not tripping until you give them 300ma is interesting.
It would be exceptional for 9 to all fail by such a margin, so I can only conclude the tester is setup wrong, the tester is faulty, there is something strange with the installation or (respectfully) you are making a mistake somehow.

A barrage of questions follow.....!
Is the main earth at the CU connected?
What exact tester are you using?
What does the RCBO say on it for I delta N, post a photo if you have one.
Are you setting it to type AC?
Have you tried testing at the output terminals with no load?
Have you already done IR testing and did you do it with the RCBO's in situ?

You can nearly detect 300ms without a tester; when you press the test button do you get an instant snappy trip or a trip after about 1/3 second.

I'll stop now....and hope someone can figure this one out!

 

[pc1966]

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?

Any 2nd opinion with someone else's MFT to rule out a test fault?

 

[Electro-tech]

This video may be useful or relevant if you prefer to do all tests. The Megger MFT feature, not sure of other testers.

 

[davesparks]

Tested 9 brand new Hager rcbos (type A) today and they only tripped when the Robin was set to 300ma.So they must be old stock?
S

So they failed the test? What did you do next?

I would have been double checking everything to make sure I hadn't made a mistake at that point.

 

[Markyd]

YOU SET THE MFT TO TYPE AC AND TEST 1X.....EVEN IF TYPE A.....EASY

 

[timhoward]

YOU SET THE MFT TO TYPE AC AND TEST 1X.....EVEN IF TYPE A.....EASY

To be completely fair I don’t think we’ve established beyond doubt that he didn’t do that.
I’d like to know which Robin tester was used and whether they are 30ma rcbos.
As this is all quite intriguing so I don’t want to scare the OP away either!

 

[sinewove]

This could easily get confusing....

Before amendment 2 they were tested at X 1/2, X1 and X5
So a 30ma RCD would be tested at 15ma, 30ma and 150ma.
They were also tested on a rising and falling wave pattern (0 degrees and 180 degrees)
The pass results were no trip at 1/2, 300ms at x1 and 40ms at x5

(I had assumed you were talking about 350ms, hence my units comment, but let's forget that.)

Since amendment 2 the minimum testing is reduced to testing at x1, so just 30ma.

Now your 2nd comment about brand new Hager Type A's not tripping until you give them 300ma is interesting.
It would be exceptional for 9 to all fail by such a margin, so I can only conclude the tester is setup wrong, the tester is faulty, there is something strange with the installation or (respectfully) you are making a mistake somehow.

A barrage of questions follow.....!
Is the main earth at the CU connected?
What exact tester are you using?
What does the RCBO say on it for I delta N, post a photo if you have one.
Are you setting it to type AC?
Have you tried testing at the output terminals with no load?
Have you already done IR testing and did you do it with the RCBO's in situ?

You can nearly detect 300ms without a tester; when you press the test button do you get an instant snappy trip or a trip after about 1/3 second.

I'll stop now....and hope someone can figure this one ou

To be completely fair I don’t think we’ve established beyond doubt that he didn’t do that.
I’d like to know which Robin tester was used and whether they are 30ma rcbos.
As this is all quite intriguing so I don’t want to scare the OP away either!

The installation is in a s/s food servery unit and is only about 3m long,so no long circuits and no loads to affect the
rcbos.Gone online and hager do,nt appear to make a rcbo above 30ma,or an s type rcbo.Will check again on Monday
and report back.The meter is a robin KMP 5404.Have just tested a wylex 32A A at home and it tests at 30ma no problem.
Regards,S

 

[timhoward]

The meter is a robin KMP 5404

I can’t give you a technical reason why but I have heard of others having problems with that tester (which is rather antiquated to be honest) and RCBOs.
A google search pulls up some examples on the IET forum.
I strongly suspect the test instrument is the issue.

 

[nicebutdim]

The installation is in a s/s food servery unit and is only about 3m long,so no long circuits and no loads to affect the
rcbos.Gone online and hager do,nt appear to make a rcbo above 30ma,or an s type rcbo.Will check again on Monday
and report back.The meter is a robin KMP 5404.Have just tested a wylex 32A A at home and it tests at 30ma no problem.
Regards,S

Your initial post & thread title stated RCD and I didn't spot the mention of RCBO when replying to your later post, hence commenting about the possibility of having received 300mA units.

While it wouldn't explain a trip current of 350mA, they certainly offer 100mA RCBOs.

 

[telectrix]

my mft is so old.it's due for pension, but it still works and done a Zs on lno tripp where a robinn came up with error---noise.

 

[timhoward]

my mft is so old.it's due for pension, but it still works and done a Zs on lno tripp where a robinn came up with error---noise.

I don’t have anything against separate testers, or old testers per se, but the old Robin Loop and RCD testers aren’t really very useful these days. Both don’t cope with RCBOs. (The loop tester is ok on the high current tests.)
I’ve known other RCD testers that draw their power from the circuit under test to do funny things with RCBOs, possibly due to inrush current.

That one doesn’t mention compatibility with 61009 devices in the manual.

If it were me I’d try the test button, as you can tell if it’s instant or 1/3rd of a second, and assuming they seem snappy I’d try another tester.
(Kt63 or 1553 are good 2nd hand buys)

 

[telectrix]

I don’t have anything against separate testers, or old testers per se, but the old Robin Loop and RCD testers aren’t really very useful these days. Both don’t cope with RCBOs. (The loop tester is ok on the high current tests.)
I’ve known other RCD testers that draw their power from the circuit under test to do funny things with RCBOs, possibly due to inrush current.

That one doesn’t mention compatibility with 61009 devices in the manual.

If it were me I’d try the test button, as you can tell if it’s instant or 1/3rd of a second, and assuming they seem snappy I’d try another tester.
(Kt63 or 1553 are good 2nd hand buys)

mine is a 1553 bought 2nd hand from a forum member 11 years ago. does everything i need apart from making beer.