Mondelez International – Europe’s largest chocolatier and owner of brands such as Cadbury, Toblerone and Oreo – recently had the old STR38S units on their two main incomers replaced by the OEM, with STR58U units, in the hope that this would stop a recurring problem with nuisance tripping. Unfortunately, the tripping just got worse.
Enduring now frequent tripping – disrupting their production and shift patterns every time – Mondelez contacted PS Electrical and asked us to investigate.
On arrival at site and following discussions with the site engineer it was clear that intensive testing had already been carried out by the site engineer.
The tripping problem on the main incomer protected by the STR58U was connected to the initiation of the large chiller plant on site, however this did not tie up with the load being drawn as the local chiller protection did not trip and the circuit had been tested and was fault free.
The incomer would trip without fault indication at a level far below its set point so the suspect STR58U and its associated AD module were the root cause and the tripping incidents were nuisance tripping as opposed to fault trips.
Our engineer replaced both STR58U units with Amp Safe Pro protection units, and full field tests were carried out to reproduce the conditions to which the STR58U units had been subjected. The Amp Safe Pro units performed perfectly, curing a costly and problem for Mondeleze as their production and continuing shift patterns were being disrupted by the spurious tripping events caused by the STR product.
PLEASE NOTE that the Masterpact M breaker is a superb piece of design and an extremely robust and reliable air circuit breaker. Replace your suspect STR devices with the Amp Safe Pro and we can offer full support to keep it in service for the next 20 years.