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Unread 09-02-2014, 13:31
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FRC #2974 (WALT)
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Re: Victor connect to 30 A instead of 40 A

Admittedly the snap action breakers we use don't have the best protection. The right fuse will clear in half a wave length. The right circuit breaker is right behind that.

Most of the legal motors have out grown the Spike since a momentary stall or loaded start will blow the fuse the spike. So that leaves the talons, victors, & jags that will happily burn out the smaller motors. Sizing the breaker closer to the running load of the motor will give some protection since that is the legal option.

In other applications... You use molded case breakers or fuses for dead short protection for motor/controllers in conjunction with overload devices that are not fast enough for a short. The rectifiers in my plant use fast acting fuses to protect solid state components. I use fuses on my plant IO so one short doesn't take down the entire control system. A typical industrial power supply will current limit & chug happily along at a dead short so wire protection is not an issue.