Why would you rather use a large DC motor over an AC one? The DC voltage used to drive that motor is as dangerous as the AC and in many cases more so because of higher amperages. Edison was a liar, read Nicola Tesla's work. For over 100 years that particular lie has been in the "common knowledge", that AC is more dangerous than DC. Both require good grounding systems and common sense. Knowledge of electricity is a definite plus.
With a DC motor you can run a low voltage, say 12 volts, but you are going to need large wires to supply the amperage required. Or you can use a higher voltage like 48 with smaller wires and a lower amperage. Basically the same idea with AC motors, you can run 110v, 220v, or even higher. Either way a watt is a watt and it takes close to a thousand of them to make a horsepower. Theoretically 746 but motors aren't 100% efficient, there are hysteresis losses and heat. Anyway, the point is that 5hp worth of DC power supply is not safer than 5hp worth of AC power supply. The energy is the same.
If you keep the motor out of the water and keep the water out of the motor and keep everything nicely bonded and grounded, up to standards, then either can be safe.
My electric barrel mixer has a 1hp 220v motor on it but the blade shaft is bent so it vibrates. I need tuits, too much else going on to fix it right now.
On 3/13/2012 9:54 AM, JayH wrote:
I don't think anyone has built one yet, but I like the idea of building a stand alone electric mixer powered by a salvaged series wound DC electric forklift motor. With careful construction it should be safe, and I would much rather work around a DC electric mixer than an AC electric mixer when a lot of water is going to be around. People are using those salvaged motors to power electric cars, so they should be more than powerful enough to make tons of papercrete.
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