A contactor is an electrically-controlled switch used for switching an electrical power circuit. Unlike a circuit breaker, a contactor is not intended to interrupt a short circuit current. Thus, a 5-inch centrifugal contactor is one having a 5-inch diameter rotor. A larger motor requires a specialized switching unit called a motor starter or motor contactor. A contactor and electronic motor controller are typically mounted to the same plate. It provides electro-pneumatic braking along with linear contactor shut-off. Power is controlled either by a contactor or a solid-state controller. Below the electron emission saturation limit the contactor acts as a bipolar emissive probe. This accelerates space plasma electrons which ionize neutral expellant flow from the contactor. A rotating biological contactor is a type of secondary (Biological) treatment process. Gas is dehydrated by counter-current contact with glycol in the Glycol Contactor. In the contactor plasma, the electron density is approximately equal to the ion density. A slightly more effective method is to make the contacts themselves larger, i.e., a contactor. This can be resolved with well placed plasma contactor. In other words, it is a particular gas-liquid contactor.