A Power Plant in the U.S. Northeast needed to monitor three safety relief valves on gas lines into their power plant. An alarm is required on each valve in case any of these relief valves experience a release of natural gas. Because it would have been too costly to run several new wires out to these valves from the control room PLC, they opted to implement a wireless solution coupled with a field mounted NCS Net Concentrator System.
Each relief valve was retrofitted with a WirelessHART positioner/monitor to relay its status back to the WirelessHART gateway. The NCS, acting as a MODBUS RTU Master, gathered the relief valve status from the gateway over RS-485 and provided the local alarming and annunciation. Alarms for each relief valve were quickly configured with easy-to-use web pages within the NCS. If any valve reported a leak, the NCS sent relay outputs to a flashing beacon and a PLC that was tied to the plant’s main SCADA and safety system.
The alarm function on the NCS system would normally be programmed using its embedded ISaGRAF control engine software, which is very powerful and versatile. However, for this straight forward multi-channel alarming application, they opted to add the –MAA Multipoint Analog Alarm option to the NCS EMM module. This option allows easy to configure alarming with prebuilt web pages that include simple pull-down menus and radio buttons., saving many hours of engineering time.