Question – I am building a dark ride. I have a choice of using AC or DC power. I am leaning towards DC power, because that is what I see many kiddy trains in malls using. My ride will be similar to the old pretzel dark rides, in which a main guide rail will be the negative side of the circuit and a small bus bar running along the side of this rail will be the positive side of the circuit. Each car will have copper pick-ups to supply power to the motor. My gearing and car design has been completed. I am trying to find someone who can help me decide between AC or DC. The DC motor choice I have is either a 12volt or 24 volt motor. If I use the 12 volt DC motor, I will need 39 amps on the rails, if I use the 12 volt DC motor, I will need 20 amps. I was thinking of using a large automotive battery charger set on continuous to power the rails. If I use the AC option, I will have to step power down from 120 volts to a safe range, and then have a transformer in each car step the power back up to the AC motor. Any guidance or recommendations you can offer me is appreciated. This project has been a labor of love for me and I want to offer a safe, reliable ride system.
Since you are just looking for some free, friendly advice, I will offer my opinion that you are better off with the DC option that you already seem to favor. I would recommend the 24 volt option, maybe even a 48 volt option if that allows a lower cost bus/pickup system. I rather expect that the pickup will be graphite and the bus bar will be copper. Wampfler is a respected manufacturer, as is Insul8 and I’m sure there are several others. Limited access to the power bus bars is key to using higher voltage AC. No one wants to lug around a transformer in the vehicle just to adjust the voltage. AC voltage allows the use of brushless motors and that will lower the required maintenance. That said, the dark ride application must assume that at some point, a break-down will force a vehicle evacuation at a track location not in the station. This is where the lower voltage bus bar is less hazardous to your guests. You still must pay attention to the evacuation route and avoid a path that puts the guests near the bus bar. The bus bar should be sheathed in insulation, regardless.
As for the power source, I’m not sure if the ride is to be portable or not, but if stationary, you could use a battery bank if adequate ventilation is available. The battery charger could then be recharging the batteries during load and unload periods. If you find one that can directly supply your current requirement, I would still consult the manufacturer and tell them your intended use to see if they concur on the suitability. A web search might reveal a DC power supply designed specifically for this kind of function. Keep in mind that the power capacity of such a supply needs to be at least equal and probably somewhat higher rated that the most severe current requirement that your vehicle(s) will need. We haven’t done any ride design like this, so there isn’t anything we would recommend.
Don’t be put off by the DC motor brush maintenance; especially if it’s just one motor. Modern DC motors are quite easy to re-brush. Just design enough access space to either access them on the vehicle or make the motor easily removable. Besides, you’ll get a lot of service from normal use as long as the motor is adequately sized. The DC option will also offer you the most flexibility in controlling the vehicle speed from the wayside, which is an important consideration.
You didn’t mention multiple vehicles, so it would seem that you don’t need a block zone system to keep vehicles separated. A block zone is required for multiple vehicles and greatly complicates a ride.
Disclaimer: These are the thoughts of the author and do not represent an engineering or legal opinion of Birket Engineering, Inc.