Holey moley - Rats will eat anything

09 July 2021

Circuit breakers are a vital piece of equipment in the safe supply of electricity. They are designed to open if a fault occurs – this disconnects electrical equipment to ensure the protection of our generators, the electricity networks and importantly, people’s lives.  


They pretty much do as the name implies - break the flow of power (220kV or 110kV of electricity) and then contain (and extinguish) the subsequent arc of electricity that’s generated. High voltage circuit breakers are also required in normal operation when starting generating assets and connecting to the electricity network and equally, when shutting down and disconnecting.


And apparently, parts of a circuit breaker can be quite tasty, like a fine matured cheese…but more about that later. 


The easiest way to think about a circuit breaker is to relate it back to your home. You know your electricity switchbox on the outside of your home? In there are fuses or circuit breakers designed to do the same job as our high voltage circuit breakers albeit on a much smaller scale.


They are used to isolate so work can be done on electrical equipment. They will also ‘trip’ (usually with a rather startling bang) if there’s a dangerous overload or fault. While you’ll be without power and possibly plunged into darkness, your home electrical wiring – and YOU - will be safe.


Unlike a fuse – which has to be replaced in your home if it trips – high voltage circuit breakers can be reset and resume their protective function.


Despite having to deal with all of that intense power that surges from our generators to your homes and businesses, circuit breakers are sturdy bits of kit, usually only needing replacement every few decades.


A view of the Gordon switchyard

One of our three main high voltage circuit breakers was up for replacement at Gordon Power Station. The team had meticulously planned the outage to minimise downtime on our generation capacity. When we’re not generating power, we’re not generating revenue so we carefully balance our safety and maintenance needs, with efficiency and commercial outcomes.


Our teams of engineers, technicians and market analysts work together to ensure we do maintenance at optimal times (and stay flexible if things need to shift to take advantage of a market opportunity).


What we didn’t bank on when starting the work was a horde of hungry rats tasting the merchandise and getting up to no gouda! We had grater plans for those instruments…


And if you’re wondering why rats would play hide and squeak with a circuit breaker (as we were), you need to know a little more technical stuff about the component parts (of the circuit breaker, not the rats). 


Circuit breakers are made up of a number of vital bits, including insulators. The insulators are used in electrical equipment to support and separate electrical conductors without allowing current through themselves (hence the term!)


The insulator “sheds” are shaped to help wash away dust and other contaminants and increase the path length between the high voltage electricity and earth.


Porcelain is the most frequently used (rat-proof) material. It can deal with higher temperatures and has a long life span. Silicon rubber is also used as it can deal with high temperatures and has the advantage of being a lighter material (which is safer in the rare event of an explosion) and more cost effective.


But apparently, silicon rubber is an under-rat-ed cheesy equivalent in the rodent world! 


With the Gordon outage shifted a couple of times to take advantage of market opportunities for generation, the circuit breaker had been in storage a little longer than normal. The sneaky silicon nibbles were only discovered when the team crane-lifted it out of the container and saw the de-brie… 

An under rat-ed cheesy equivalent!


Thanks to a hole lot of quick thinking, a non-nibbled circuit breaker was sourced from another station and we were able to get on with the replacement task with minimal disruption to the schedule. In fact, the team completed the work ahead of time and Gordon was back online a few days before anticipated.


So the next time you drive past a substation, you’ll have a new appreciation for the life-saving role of a circuit breaker and the clever and resourceful teams who keep our stations running.


And to the rats – cheddar luck next time!


Thank you for the comment! Your comment must be approved first
Load more comments


The intake tower 200 metres above Gordon Power Station

Gordon gets a new lease on life >

If life begins at 40, as the saying goes, it began this year for one of our most iconic landmarks. But clocking up four decades of dedicated power generation for Tasmania had taken a toll so this year Gordon Power Station has undergone one of its biggest maintenance operations yet.

The legacy of John Butters >

It’s not every day that a power station evokes tears of sentimental joy but that is precisely the effect the John Butters Power Station had on one special visitor recently.

Grad program banner

Graduating to the next level >

What's it like being part of Hydro Tasmania's Graduate Program? Maria Brescianini shares her experience as a graduate mechanical engineer and also provides a few tips on how to nail your application.