Robin De-lock Loop Tester

[somersetsparks]

Hi all,
Just wondered if someone could tell me why my Robin Loop Tester with de-lock will only test through BS4293 Rcds? As soon as I use it on a 61008 or 61009 it will trip it?
I do normally use a megger with de-lock and its fine, but I like to use the robin for industrial/commercial tests.

 

[MarkieSparkie]

Robin's D-lock method of ELFI testing attempts to desensitise the RCD by swamping it's mechanism with DC 'blocking' voltage as part of the high current loop test pulse. This method works with BS4293 RCDs, but the newer BS EN 61009 types are much more testing-sensitive and D-lock is very often not effective.
Megger have never used the DC blocking method as it was covered by Robin patent. Initially Megger used a variation of the now common single pulse low current (15mA) EFLI test method which injects a current below the residual trip current of the RCD. Later this was superseded by their patented low current multi-pulse method that is much less sensitive to electrical noise.

 

[somersetsparks]

Shame, as I have always liked the robin, on an old rcd, it tests instantly and gives 'true' results with its 20A test, oh well Il keep it for the industrial stuff then!