DDG-51 CLASS CHILLED WATER AUTOMATION SYSTEM (CWAS) LAND-BASED PERFORMANCE TEST (LBPT) FACILITY CONTROL AND MONITORING SYSTEM (CMS)

A Chilled Water Automation System (CWAS) is currently under development for deployment on DDG-107 and follow.  The system is to provide automated damage control for the ship’s chilled water plant. It is to rely on programmable automated valves (PAVs) – or smart valves – and flow sensors installed in the CW plant expansion tank outlet piping to detect and isolate ruptures within the closed-loop piping system.

To test the CW system being developed, a Land-based Performance Test (LBPT) facility was constructed at the Naval Surface Warfare Center (NSWC) Land-Based Engineering Site (LBES) in Philadelphia, PA. NSWC was tasked to design, construct, and operate the CWAS LBPT facility to support CWAS performance testing. NSWC in turn tasked Fairmount Automation to design, develop, and integrate the Control and Monitoring System (CMS) for the CWAS LBPT facility.

The need for the CMS was established by the rigorous testing requirements of the CWAS. The requirements related to the design (and usage) of the CWAS LBPT facility are described in BIW Purchase Specification 503-532-12A, “Purchase Specification for Chilled Water Automation System for DDG-51 Class Ships,” which states “CWAS shall be tested…using a full-scale, reduced-scope demonstrator to verify the damage detection, isolation, and reconfiguration capabilities [of CWAS]. The test shall provide a means to simulate fluid system damage across the full range of chilled water operating conditions, as well as individually interrupt distributed control network communications between CWAS node[s] and electrical power to each CWAS node.”

Fairmount Automation’s tasking included the design of all CMS hardware configuration items (HWCIs), the design, coding and testing of all CMS software configuration items (SCIs), and the development of human computer interface (HCI) software. The CMS provides the following capabilities to support the CWAS LBPT facility:

  • Capability to remotely control, and monitor the operation of the port chilled water loop (including the chilled water plant that supplies the port loop).
  • Capability to activate ruptures in the port main loop and branch piping, interrupt (break) each DCN segment between CWAS nodes, and interrupt electrical power to each CWAS node.
  • Capability to log test data (e.g., damage events imposed by the CMS, as well as pressures and volumetric flow rates in key locations of the port chilled water piping and plant).

Fairmount Automation was also responsible for generating the CMS validation test plan and test procedures and for submitting these documents to NSWC Code 923 for review and approval. Fairmount Automation and NSWC Code 923 personnel jointly conducted CMS validation testing. CMS testing verified:

  • The CMS provides the capability to independently control each rupture simulation valve from the Test Operator Workstation (TOW) and verify the CMS data logging.
  • The CMS provides the capability to independently interrupt each DCN segment from the TOW and verify the CMS data logging.
  • The CMS provides the capability to independently interrupt power to each CWAS component from the TOW and verify CMS data logging.
  • The CMS provides the capability to control and monitor the chilled water plant including displaying pump discharge and suction pressure, expansion tank level, array supply pressures, and expansion tank level alarms, remotely starting and stopping the pump, automatic shutdown of the pump on low level condition, and emergency shutdown of the pump. Additionally, data logging of all plant parameters with correct timestamps will be verified.
  • The CMS provides the capability to control and monitor the chilled water branches including remote control of valve position, automatic control of branch flow, indication of branch flow rate, and indication of valve position feedback. Additionally data logging of all branch flow parameters with correct timestamps will be verified.
  • The CMS executes damage scenarios properly by verifying rupture valve relays, DCN interrupt relays, and CWAS power interrupt relays activate at the times defined in the damage scenario file. Additionally, ensure that the CMS automatically logs data during the damage scenario and that damage scenario execution may be halted via stop scenario command and/or emergency shutdown command.

The CWAS LBPT facility design includes a full-scale, port chilled water loop (5-inch diameter piping and approximately 300 feet in length), and a simulated starboard chilled water loop, architected by Fairmount Automation. The port loop contains actual PAVs, while the starboard loop contains simulated PAV nodes interfaced to a computer-based simulation of the starboard loop. The CWAS vendor is providing the simulated PAV nodes and computer-based simulation to implement the simulated starboard chilled water loop. The CWAS LBPT facility also includes the complete CWAS distributed control network (DCN) infrastructure (i.e., all CWAS nodes, gateways, routers, and DCN segments).

Following successful CMS qualification testing, Fairmount Automation turned over the CWAS LBPT to the CWAS test team to support qualification testing in August 2005.