For the operation of treatment equipment, whether a soil vapor extraction system or membrane biological reactor, some form of control system is necessary. Most treatment equipment will have a variety of control inputs (level switches, emergency stop buttons, etc) and outputs (electric motors, lights, etc.). In order to process these inputs and control the outputs, a control system is necessary. Control systems come in two basic forms: relay based, and PLC based.
A relay based control system uses a number of electrical relays to transmit signals from control devices to operating equipment. Relay based control systems are often used for simple control systems. Due to the number of relays involved in larger systems, PLC based control systems are more common. There are fewer telemetry options available for relay based systems as well.
In a PLC based control system, a programmable computer receives input signals from the equipment being controlled, processes this information using the structure and rules entered into the program and then controls outputs that operate equipment. PLC based control systems are flexible in the range of operations they can control and are easily modified, enhanced or altered, even after the system is installed. Changing the logical sequence of events in the operation of a system to adjust to changing operating conditions or adding new equipment to be controlled is usually as simple as a small amount of programming. These systems also offer a range of user communication options.
Telemetry is used in combination with both relay based and PLC based control systems, allowing the control system to communicate with a remote operator, a remote operator to communicate with a control system, or both. Options for telemetry include: autodialers for alarm notification, daily email status updates, direct linking to system for monitoring and control, and web-based linking to system for monitoring and control.
Please follow the links to view the various types of control systems and telemetry options.
