Morning everyone, this is my first post - although i had an account years before that seems to have been lost.
Can any of you shed some light onto a situation I've come across.
I have a newly installed RCBO which is failing the x5 test with a reaction greater than 40 mS.
Now, I don't have a problem with that as some devices do fail straight from the box but.... it's the manner in which it fails that I find perplexing.
It's a Type A b curve CP Fusebox RCBO at 40A - so admittedly budget kit.
When tested on the testers AC setting it tests fine - 30mA and 150mA both causing sub 40mS activation at 0 and 180 deg.
However on the type A setting it activates at greater than 40mS on x5 BUT it activates at 36mS on x1 at both 0 and 180.
How can it be that it can activate at the lower fault level in a time that would satisfy the higher fault level test but then go on to fail the higher fault level test?
I'm not sure exactly what the tester does for the Type A tests but I assume it just introduces a DC current whilst the test is in progress along side the simulated AC fault current. I thought then that the AC current is increased for the x5 test whilst the DC component stays the same. If this is the case then the result seems very confusing.
Mybe the DC component of the test is also increased by the tester for the x5 test but I wouldn't have thought that would be the case as they are for up to 6mA DC and you'd think that is the current used by the tester for both x1 and x5 tests.
I don't mind swapping the device out but I'd just like to understand why it's happening.
Any ideas?
It's a new tester BTW - Metrel MI3152 - which I'm still getting to know. But the settings used in the tests are the standard ones for a 30mA General use RCD on both type A and AC.
Thanks
Can any of you shed some light onto a situation I've come across.
I have a newly installed RCBO which is failing the x5 test with a reaction greater than 40 mS.
Now, I don't have a problem with that as some devices do fail straight from the box but.... it's the manner in which it fails that I find perplexing.
It's a Type A b curve CP Fusebox RCBO at 40A - so admittedly budget kit.
When tested on the testers AC setting it tests fine - 30mA and 150mA both causing sub 40mS activation at 0 and 180 deg.
However on the type A setting it activates at greater than 40mS on x5 BUT it activates at 36mS on x1 at both 0 and 180.
How can it be that it can activate at the lower fault level in a time that would satisfy the higher fault level test but then go on to fail the higher fault level test?
I'm not sure exactly what the tester does for the Type A tests but I assume it just introduces a DC current whilst the test is in progress along side the simulated AC fault current. I thought then that the AC current is increased for the x5 test whilst the DC component stays the same. If this is the case then the result seems very confusing.
Mybe the DC component of the test is also increased by the tester for the x5 test but I wouldn't have thought that would be the case as they are for up to 6mA DC and you'd think that is the current used by the tester for both x1 and x5 tests.
I don't mind swapping the device out but I'd just like to understand why it's happening.
Any ideas?
It's a new tester BTW - Metrel MI3152 - which I'm still getting to know. But the settings used in the tests are the standard ones for a 30mA General use RCD on both type A and AC.
Thanks
