Soft Starters

SamL · 11-04-2007, 11:15 PM

After attending the 2007 Nationals, we were all shown how a simple a 2 step electrical pre-rotator soft starter is to make and fit.
I have attached some photos of the ones fitted to gyros at the Nationals.
My questions are

1) in order to reduce the voltage during initial rotation (first stage) a resistance wire is used. What type of wire is it? and what gauge is it? also what is average price?
2) What size solinoid (? amps) are people currently using? and price?
3) In order to automatically transition through to second stage a timer is being used. what type of timer is it? were is it from? and how much does it cost?
4) Has anyone thought of using solidstate relays, as they are cheaper to buy, smaller, more reliable, and consume less power.

Sorry for the many questions, but I have already made some enquiries on the above, and am after the best fit solutions.

Regards SamL.

SamL · 11-04-2007, 11:16 PM

More pic's

Echo 2 · 12-04-2007, 01:19 PM

Sam,
from what Owen told me ,that resistor wire is a length of stainless steel , heat it up & bend it around to make it coil .

SamL · 12-04-2007, 01:51 PM

Thanks Echo.
I did hear that on the weekend, but also heard about some sort of Nickochromium wire used in strip heaters.
Am currently looking into using a DC controlled 100 amp MOSFET to switch the 50-80amp starter.

Sam......

niquenaque · 12-04-2007, 06:59 PM

Sam,

Save yourself a large amount of trouble and speak with Ross Bannerman [0421342877] about the starter he built using mosfets.

His handle is RossB on the ASRA forum - not so sure about here.

Cheers,

Nick.

SamL · 12-04-2007, 09:52 PM

Quote:

Originally Posted by niquenaque

Sam,

Save yourself a large amount of trouble and speak with Ross Bannerman [0421342877] about the starter he built using mosfets.

His handle is RossB on the ASRA forum - not so sure about here.

Cheers,

Nick.

Thanks Nick, I will do that. The only hickup with these solidstate devices is they require a heat sink to dissipate the heat produced during switching. This adds cost and size to the installation.
Sam.

Adrian S · 03-07-2007, 12:50 PM

Guys,

We have done agreat deal of R&D in this area over the past few years. I strongly recommend you talk to Pete Barsden (Assist Tech Manager West) on this as we have found that alot of pre-rotators draw in excess of 180 to 250amps on initial start and mosfet systems cease to be cost effective and reliable(heat disapation is a real issue with this level of current). I was trialing a brilliant system built by Pete - stepped RPM from 0 to 150 but the real costs to produce and get to market would have exceeded $500.
The systems that use a resister wire can be built for between $50 for a very basic system similar to Owen Dull, Mitch or John Evans to $150 when you put a timer in the circuit similar to what myself and the other guys in WA use.
My advice is keep it simple and cheap. Of course the cheapest soft start is to hand start prior to engaging the pre rotator!

Adrian
PS dont hesitate to call me if you want more detail.
Mob 0427094552