Avoiding downtime in steam engineering with alarm monitoring

In large engineering plants, it can be difficult to identify when a circuit breaker has been tripped, especially when navigating multiple subplants across an industrial site. This can prolong any downtime, halt production and ultimately cost the manufacturer money. Ian Loudon outlines how its sequence of events recording technology in the mechanical and engineering sector plays a pivotal role in keeping things online

When a plant has multiple substations, many electrical appliances across its operations require monitoring. Each substation needs to monitor its circuit breakers to identify if they have been tripped or not. If there has been a fault, diagnostics need to quickly locate the root cause of the problem before bringing the plant back online again. Sequence Event Recorders (SERs) play a key role in identifying these faults.

Many events, such as electrical overloads, are a big cause of downtime. Fixing that quickly, therefore, is a huge money saving. Therefore, any system that is implemented must be able to quickly identify and rectify the fault. Rectifying the fault can be the easy part, but this can be tricky in a plant with hundreds of circuit breakers.

Omniflex has worked with steam engineering specialist ThyssenKrupp, where each substation has alarm annunciators to provide a visual indicator of which circuit breaker has been tripped. By having a SER installed, its time stamping capability records every event to the millisecond – providing plant operators with the visibility of which circuit breaker tripped first. This aids any maintenance worker with locating and rectifying the fault in the plant.

In addition, each system has a GPS time synchronisation module integrated into the device. As one substation can affect another across an entire plant, this provides visibility of which order each event occurred in.

Working in tandem

Alongside SERs are alarm annunciators. Though the two can work separately, working together to monitor the same trip contact is more effective. Normally, this requires a lot of wiring, but this can be simplified with one set of terminals. This can be done with a specific printed circuit board to split the alarm signals to the annunciator via a ribbon cable, with another cable part of the connector into the SER. By splitting the inputs, you can save on wiring. The inputs are wired to terminals which then, using the PCB, splits alarms to the annunciator on a ribbon cable and the sequence of event signal to the recorder on a DB37 cable. This cable easily plugs in to connect and disconnect, eliminating wiring faults and potential loose connections.

Two phases

For this project, Omniflex provided its Maxiflex SER system, which works alongside its Omni-4000 based alarm management package and other SCADA systems. On a previous project twenty years ago, Omniflex provided its SER260 predecessor, which provided the diagnostics required. Subsequently, ThyssenKrupp expanded the system when they were commissioned to engineer a new steam plant. The latest Maxiflex SER system, along with its GPS capability, could then provide these timestamps to identify when and where the fault had taken place.

It provided local substation alarm visualisation at up to 256 points capacity at each substation, with the plant wide electrical alarms time synchronised for sequence of event recording – allowing faults to be easily identified. All fault alarms are synchronised to the same time base with better than 1 millisecond resolution

With the Maxiflex SER, time synchronisation is done from a time sync master in the system that can be configured to be a Maxiflex CPU or the PC based Omni4000 or SCADA. In each case, broadcast time sync command is provided to all the Maxiflex devices connected to it. This means that in the typical situation, where an external master time sync system is used for the entire plant, the computer is updated according to the external master and the open platform communications server will broadcast updates for the Maxiflex SOE system.

Ian Loudon is international sales and marketing manager at remote monitoring and alarm annunciator specialist Omniflex.