Requirement:

The new control system should provide an open architecture and increased functionality based around modern PLCs and linking into an existing telemetry database, helping to reduce the maintenance burden associated with an ageing, custom-designed system, whilst providing a ready upgrade path to meet any future requirements. It should also meet power supply concerns enabling continued conversion from diesel generators to solar and wind power.

Omron Solutions:

With 72 facilities to upgrade, Trinity began at the Cromer lighthouse on the Norfolk coast. With Trinity’s project team driving the specifications for the installation, Omron’s application engineers developed a control strategy built around the powerful CS1 PLC as a control hub, with CPM2C micro PLCs networked to the CS1 over DeviceNet and providing local control of critical systems.

The CS1 acts as the network hub for the lighthouse control system – providing what Richard Tomkins, the project engineer describes as a ‘general systems’ PLC. It facilitates the networking capability of the aids to navigation and ancillary systems and controls lighting throughout the tower, security systems and acts as the monitoring interface with the telemetry system. Each Aid employs its own CPM2C enabling it to continue operation independent of the condition of the other systems in the lighthouse.

Fully Integrated Solutions

The main light CPM2C controls the timing sequence for striking up the metal halide lamp, and indirectly monitors the incandescence profile of the lamp. It also monitors the rotation frequency of the optic, and rotating out a failed lamp and rotating in a new lamp. Other CPM2Cs control and monitor functions such as activating fog warning systems, and switching between and managing the main and back-up battery systems. In addition, since the commissioning of Cromer the CPM2C battery management system has been further developed to control a hybrid solar/wind power system. Operating in conjunction with an Omron E5CK process controller, networked via an RS485 communications link, the system monitors parameters such as charging current and battery temperature, to maintain the full complement of batteries in optimum condition and take appropriate action in the event of a problem or alarm condition.

For engineers visiting the facility, the control system provides a human-machine interface (HMI) front end for set-up and maintenance. “The HMIs are particularly effective,” says Tomkins. “They simplify set-up, and provide our maintenance teams with much more information about the system. This means maintenance can be more efficient, and so more cost-effective. Rather than using a fixed HMI, we’ve provided sockets at each PLC which are distributed throughout the lighthouse, so you can take a mobile HMI around with you and plug it in wherever it’s convenient.”

The officers at the Harwich Operations Centre rely on remote monitoring of the control system. As standard, the telemetry system at the Harwich Operations Centre dials up each lighthouse twice a day, allowing the operators to make a systematic check of all the analogue parameter values and system status, and look for problems. The CS1 provides a seamless link with the telemetry system via ModBus, making all the relevant data easy to access. Any alarm event automatically triggers the telemetry system to dial out to the Operations Centre.    

Trinity House Lighthouse Service chose Omron because:

"It was important to us that we worked with a company that had demonstrable experience in automation and telemetry systems, in application areas where there were similar problems and concerns. We were also looking for a partner who would make a commitment to a high level of support. Omron really stood out as having the necessary combination of products with the technical features we needed, people with the necessary applications background, and - most importantly - the willingness to provide the backup and support we required," says Richard Tomkins, Project Engineer.