pressure system. The filter pump runs all the time and the main pump runs at the same speed whether it is cutting or sitting idle—so the fluid is constantly circulating to maintain thermal stability. This becomes a significant drain on energy. Today's machines are more environmentally and friendly—having evolved in many areas to dramatically reduce their energy footprint. Digital anti-electrolysis generators do a better job of shaping the cutting pulse and reducing the ions generated in the water; this reduces the load on the DI resin system—allowing it to last up to three times longer. Some systems use a power regeneration circuit, which stores the over-current to create the next ignition pulse. This eliminates the bank of resistors found on the old DC generator—and the heat they produce—for decreased energy usage. New fluid systems have more pumps that are designed specifically for various functions, and therefore run less often. The main pump is now an inverter-type unit that changes speed to control water volume and pressure and only pushes water to the cutting heads when the machine is running. Separate, smaller pumps now manage the fluid circulation system—running water through the chiller and the machine to maintain thermal stability at a much lower cost. The machine can also operate in a cost save mode that reduces wire consumption and puts the machine to sleep after the job is complete; in this sleep mode, the energy usage is equal to that of a 100-watt light bulb.