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Kalyan Dash
07-03-2013, 09:19 AM
SAE International rule-2013:
EV3.5.1 In every accumulator container at least two isolation relays must be installed.

Can we use main contactor as isolation relay?

Kalyan
TMichaels
07-04-2013, 03:18 PM
What is the difference in your opinion?
Kalyan Dash
07-04-2013, 11:37 PM
Sir, both main contactor and isolation relays perform the same action.

Kalyan
TMichaels
07-06-2013, 12:27 AM
If it sits inside the accumulator container then I do not see a reason why not. But it is always better to ask the Rules committee of the event that you plan to attend.

And please don't call me Sir, I work for my money http://fsae.com/groupee_common/emoticons/icon_wink.gif
Kalyan Dash
07-09-2013, 01:38 AM
Is it permissible to use circuit breakers as accumulator isolation relays?
jd74914
07-09-2013, 04:34 AM
I don't have a "rules correct" answer for that question, but it is bad practice to use circuit breakers as switches or really anything besides wire protection for that matter.
Kalyan Dash
07-09-2013, 05:46 AM
What about a simple SPST relay?
Adam Farabaugh
07-10-2013, 12:40 PM
What's the difference between a contactor and a SPST relay?
Kalyan Dash
07-11-2013, 12:55 AM
The main contactor is double the size of a SPST relay and heavy also.
jd74914
07-11-2013, 07:03 AM
Adam is not referring to the physical size difference. He really means:

"What is the functional difference between a contactor and SPST relay?"
Goyds
07-11-2013, 07:33 AM
G'day all.

Functionally a contractor, isolation relay or whatever you want to call them is just an electrically actuated single pole switch. In this way they are exactly a SPST relay.

A "contactor" is really just a large relay however it is important you don't skimp on these components as they are a key safety device and must not be used outside their ratings.

If anyone is looking I'd recommend finding a vacuum type unit as they are smaller, lighter and more reliable and are ideal for our use.

Oh and no, i don't think a circuit breaker would be ok for a isolation AIR as you'd need to switch it when the traction system is disabled (I.E. the crash sensor trips) and there is no safe way of doing that deliberately for most circuit breakers.

As always, ask the rules committee if you have any concerns about your choice.

Lloyd Morrissey
Chief Engineer
Team Swinburne 2012