[OCCRA]: Dewalts Blowing Fuse

[nfhs]

We have been having the problem the past few compititions with our fuses blowing, we were wondering if we could just put a 12 ohm resistor to lower the amperage going to the motors.

[Mike Martus]

Question: We have been having the problem the past few competitions with our fuses blowing, we were wondering if we could just put a 12 ohm resistor to lower the amperage going to the motors.[/quote]

Answer: That will not help. Have you investigated what will happen to the motor output when you lower the amperage.... There are formulas for this....... What you need to do is to see why you are exceeding the current limit of the breaker.

Several Considerations:

• Are you using the 35 amp breaker? We have them available.
• The work you are asking the motor to do may be drawing more that the breaker allows.

The load upon the motor is critical. Proper gear ratio will lessen the load and stop the breaker from tripping.

Think of it this way.... I am sure you have been on a 10 speed bike... what happens when you are asked to do more work with your legs, such as going up hill. With the wrong gear ratio, part the way up the hill you stall ( breaker trips) and you stop. That is what is happening to the motor. The breaker prevents the motor from damage and turning your electrical system into a toaster.

Problem: Fact of life: you cannot have both speed and power FACT! Well, unless you change gear ratio such as a shifting transmission.

Next point: Friction is your enemy! Look for friction points as they cause the motor to work harder.

Remember you have 1 hour per week for expert design review. Have someone that is knowledgeable about this look at your robot. Do this early so you can change what needs to be changed.