Circuit Breakers TM

[pootnic]

Lets say for a trolling motor I need 4/6 gauge wire to handle a 50amp breaker.
Thats some good diameter wire.
I'm trying to understand or get it through my thick head,why don't the little wires in the trolling motor melt before the breaker trips?(if it has to)
The smaller diameter wires in the TM must not be part of the circuit?
Transformers,stepped down,overload protection???
I know the breakers work,not doubting that,just trying to get a better understanding of whats going on.

 

[Don S]

Re: Circuit Breakers TM

Resistance is the reason. A long run of 15 feet has more resistance than a run of 2-3 inches.
Look at some of the wiring size charts, you will see that the longer the run, the larger diameter of the wire.

 

[Silvertip]

Re: Circuit Breakers TM

When a motor is specified at a specific amperage "maximum", that rating is generally at stalled rotor meaning full power is applied but the rotor isn't turning. There will also be a short period during motor start where current in-rush is high. But generally the current demand for a motor is much less than the specified "maximum". The breaker is there to protect against a short in the run of cable going "to" the motor as well as the motor itself. Starter motors, generators, and any electric motor for that matter if operated at its maximum current draw for any amount of time will obviously fry.

 

[pootnic]

Re: Circuit Breakers TM

Thanks for the replies.
I realize the TM doesn't run at full amperage all the time.
I was just thinking the smaller wires and circuit boards couldn't handle the amperage even for alittle while,thought they should act almost like a fuse.
The windings around the motor are small and probably really long,they must not ever get 50/60 amps on them.
I was thing the TM could control how much amperage went where..transformers etc.
Let me ask this:
Would a complete circuit go from the positive side,through the circuit breaker, to the TM(through the pot.,circuit boards,down the winding and back up etc.)then back to the neg.side of the battery?
Approx.10 to 60 amps flows all through the TM at certain periods throught a day?
Wish I could word better questions...

 

[Silvertip]

Re: Circuit Breakers TM

Thats what you call a "complete circuit" but everything is not connected in serial fashion. Once current gets to the foot pedal various circuits are enabled or disabled depending on what speed or mode you have selected. Speed control is not via a rheostat but rather an electronic package that pulses the motor. The closer the pulses are together the faster the motor runs until pure DC is fed which is now full speed. Older motors used various ways to control speed from speed coils to electronic speed controls. Much of the energy is wasted as heat in those systems.

 

[TerryMSU]

Re: Circuit Breakers TM

Thats what you call a "complete circuit" but everything is not connected in serial fashion. Once current gets to the foot pedal various circuits are enabled or disabled depending on what speed or mode you have selected. Speed control is not via a rheostat but rather an electronic package that pulses the motor. The closer the pulses are together the faster the motor runs until pure DC is fed which is now full speed. Older motors used various ways to control speed from speed coils to electronic speed controls. Much of the energy is wasted as heat in those systems.

Don:

I think everything is wired mostly in series fashion. Almost everything in the main power wire goes directly to the motor armature. The wire in the motor armature is always moving and thus a lot of the heat is transferred away from the armature by the moving air Also the wire is wound on a iron core which also draws the heat away from the wire. In addition the power wires are insulated with rubber or vinyl. It is the vinyl or rubber insulation that is the concern. It will melt long before the insulation in the motor or the circuit board. The vinyl or rubber also acts as a thermal insulator trapping the heat inside that power lead wire.

TerryMSU

 

[Silvertip]

Re: Circuit Breakers TM

We are nit-picking the series thing. Yes -- the various assemblies that control a troller can be considered "physically" placed in serial fashion. Foot pedal-head-motor control board-and armature from a functional flow viewpoint. However, the controls in modern motors are not simple series straight shot to the motor circuits. Electronic asemblies are full of solid state devices, resistors, diodes, capacitors, potentiometers, switches, and those are configured in any number of circuit configurations. As for motor cooling, the motor is under water. There is no air circulation/exchange in a trolling motor housing.

 

[pootnic]

Re: Circuit Breakers TM

I was just trying to figure out the current flow a bit better,I guess inside the TM more then anything.
I know theres different types of same gauge wire that can handle different amperages and shorter wires don't need to be as thick,etc,etc.I just found it "weird" that some of the small TM components can handle such high amps.
I guess it really doesn't matter, I know trollng motors and circuit breakers work,so I should stop thinking about it.
I am wondering now if a 24 volt would out last a 12V TM,due to the heat(amp)issue.Probably the manufactures just use minimun wires,components to handle the volts,amps necessary not making any difference.