Casino industry power system experts discuss the design challenges associated with properly distributing AC power to equipment on the casino floor.



Recently, I hosted discussions with casino industry power system experts about the design challenges associated with properly distributing AC power to equipment on the casino floor.

Most people looking at a large casino gaming floor see a forest of slot machines punctuated by a rectangle of table games. On the other hand, my expert friends see through the floor’s carpeting to the AC power distribution infrastructure under the floor.

My expert friends say that within a typical 200-by-200-foot swath of gaming floor-excluding the gaming table section-there are upwards of 2,500 slot machines sitting on above floor pedestals. Each pedestal supports between four and 16 flashing, noisy but appealing machines. And, each slot machine consumes 200 to 400 watts of 120VAC power from a centralized power source connected through a building code compatible AC distribution system.

Below the gaming floor carpeting, a series of long, parallel, fabricated metal trenches is sunk into the concrete foundation. They run from one end of the casino (close to the main AC power source/protection panels) all the way to the opposite end of the casino gaming floor. Depending on the size of the casino, this length can be on the order of 300 to 1,000 feet. To provide for flexibility of slot machine pedestal placement, the trenches are configured with game machine power service attachment points (PSAPs-every two to four feet) all along their length. And, the casino layout designer locates the slot machine pedestals just above the PSAPs.

Bundles of power cables are laid into the trenches with each cable terminated at a breaker in the main AC panel. At the other end, each cable is terminated to a PSAP.Slots are installed on their pedestals and the AC line cords for (up to) four machines are connected to a PSAP just below the floor.

Now that we know how AC power gets to all those slot machines, it’s time to talk a bit about how a typical slot machine uses that power. Each machine is equipped with (basically) a computer power supply that converts the incoming 120 VAC line voltage and into (mainly) 5 and 12 Volts DC power. This power is used to run the slot machine’s microprocessor based control/communications circuitry, audio circuitry, a bill acceptor, and visually appealing LCD/LED displays.

Getting back to the power system experts, they emphasized that casino operators and engineers expect that all the system elements must be: affordable; reliable; efficient; extensible /upgradable; and maintainable. Unfortunately, some of these requirements get in the way of meeting all of these requirements. For instance, casino budgets issues impose limits on the dollars available to address all the other requirements. So, there is a constant battle between the affordable and the desirable. During my research, I talked to Carl Cardi, president of CVC Limited 1, a manufacturer of AC cable trench inserts, and he described the following:

The number of AC cables physically bundled into the trenches is not limitless. You’d think that this hard limit would set the overall system’s extensibility/upgradability, figuring that each cable supports current delivery for (up to) four slot machine power supplies. However, unfortunately, well before you approach the cable/trench limit, the cable power losses and the difficulty of cooling trenches crammed with cabling causes the bundle temperature to rise above the temperature specification of the individual cables. And, after a time this condition can result in unexpected cable and connector failures.

Putting things into prospective, you usually don’t think of cabling laid in a trench as requiring a hi-tech solution to make it function reliably. But right now, for casinos that are experiencing cable bundle overheating issues, the recommended solution involves running thermal scans (twice a month) to detect failing cables. Of course, when a problem is detected, it must be pulled, replaced, reconnected and tested before the associated slot machines are again functional. All these maintenance operations are very expensive and time consuming.

The trench inserts provide all the cable bundles with a conductive cooling path to the metal trench walls, restoring the bundle temperatures to a safe operating temperature range. So, as Carl tells it, a cost trade study showed significant savings-in maintenance, reducing downtime, and restored machine productivity-resulted by implementing the inserts rather than performing the twice monthly maintenance operations. So, unusual as it sounds, this example can best be described as a case where enhanced system performance was achievable and affordable through the use of a new upgrade technology.