Just out of curiosity..

Posted by Gui Cavalcanti at 03/17/2001 6:10 PM EST

Student on team #422, Mech Tech, from Governor’s School (GSGIS) and Verizon.

What would cause a spike relay fuse to blow out? I have one here in my hand, a “souvenir” of regionals, as it were… I found it on the floor when we were leaving, and the little filament inside is broken. I didn’t think that could happen on a spike relay. Any ideas as to what caused this?

Programmer-who-shouldn’t-be-dabbling-in-electrical,
Gui

Team 422 (Mech Tech)

Posted by Lloyd Burns at 03/17/2001 10:49 PM EST

Engineer on team #188, Woburn Robotics, from Woburn Collegiate and TorDistSchoolBrd, ScotiaBank. OntPwrGen, Enbridge.

In Reply to: Just out of curiosity…
Posted by Gui Cavalcanti on 03/17/2001 6:10 PM EST:

: What would cause a spike relay fuse to blow out? I have one here in my hand, a “souvenir” of regionals, as it were… I found it on the floor when we were leaving, and the little filament inside is broken. I didn’t think that could happen on a spike relay. Any ideas as to what caused this?

. One thing that causes this (and has for at least three years) is the starting current drawn by a compressor trying to start pushing air into a pressurized air system. The pump, once it gets going, only needs about 8 A, but when the pressure keeps the pump from going through the first cycle, the motor can’t move, can’t generate "back e.m.f., and can’t help but draw “locked rotor current” of about 25+ A.

. I saw it happen to another team this year. It might be avoidable if the compressor-starting pressure (of the pressure switch) were set to a lower figure.

: Programmer-who-shouldn’t-be-dabbling-in-electrical,
: Gui

: Team 422 (Mech Tech)

Posted by Travis Hoffman at 03/18/2001 9:07 AM EST

Engineer on team #48, Delphi E.L.I.T.E., from Warren G. Harding High School and Delphi Automotive Systems .

In Reply to: Just out of curiosity…
Posted by Gui Cavalcanti on 03/17/2001 6:10 PM EST:

: What would cause a spike relay fuse to blow out? I have one here in my hand, a “souvenir” of regionals, as it were… I found it on the floor when we were leaving, and the little filament inside is broken. I didn’t think that could happen on a spike relay. Any ideas as to what caused this?

: Programmer-who-shouldn’t-be-dabbling-in-electrical,
: Gui

Try using a red Spike as a fuse block for a 12VDC supply line (this is used on our war wagon, not our robot), and watch as an misinformed student plugs the battery ground directly into M-. POOF.

Travis

: Team 422 (Mech Tech)

Posted by Matt Leese at 03/18/2001 9:54 AM EST

Other on team #73, Tigerbolt, from Edison Technical HS and Alstom & Fiber Technologies & RIT.

In Reply to: Just out of curiosity…
Posted by Gui Cavalcanti on 03/17/2001 6:10 PM EST:

A fuse would blow any time you overload the circuit. that includes the fuse. There are a number of things that can do this including trying to have your motor draw too much current (I’m not sure what the fuses are rated to of the top of my head so the breaker MAY trip first). Another thing that could happen (and in my opinion is most likely) is that there was a short somewhere in the circuit and it just took the fuse with it. By taking the fuse, it saved the spike.

Matt

Posted by Nate Smith at 03/18/2001 12:30 PM EST

Other on team #66, Frostbite, from Willow Run High School and GM Powertrain.

In Reply to: Re: Just out of curiosity…
Posted by Matt Leese on 03/18/2001 9:54 AM EST:

: A fuse would blow any time you overload the circuit. that includes the fuse. There are a number of things that can do this including trying to have your motor draw too much current (I’m not sure what the fuses are rated to of the top of my head so the breaker MAY trip first). Another thing that could happen (and in my opinion is most likely) is that there was a short somewhere in the circuit and it just took the fuse with it. By taking the fuse, it saved the spike.

: Matt