When a consulting engineering company approached ABB about a particular problem that its platinum mining client was experiencing at its smelter facility in South Africa’s North West Province, it was an opportunity for ABB, as a technology provider, to demonstrate its innovation and adaptability in responding to specific customer requirements. Engineering Manager at ABB, Jan van Zyl says the problem presented was nuisance tripping of the furnace, “due to an assumed earth fault caused by an unbalanced inrush current on the transformer”.
Switchsync® PWC600 is designed for single-pole operated circuit breakers, controlling each pole to close or open at the optimal point.
The solution devised was based on using the on-point switch capability of the Switchsync® PWC600. This relay is designed for single-pole operated circuit breakers, controlling each pole to close and/or open at the optimal point on the wave where inrush currents and flux generation are the lowest for the switched load.
It features a high level of flexibility for switching various loads with diverse configurations and comprehensive monitoring functionality to track circuit breaker behaviour and for handling multiple loads connected to the same breaker. For power transformers, PWC600 can estimate the residual fluxes in the core to minimise energisation transients under all switching scenarios. It compensates for variations in environmental factors and drifts in circuit breaker properties.
Implemented at the smelter facility, the solution resulted in a significant reduction of downtime and production losses for the platinum miner. “The client’s main aim was to increase the efficiency of the furnace by removing all the nuisance downtime – and so boost its profitability considerably,” says van Zyl.
Fanie Delport, Sales Specialist at ABB, says this solution has now been adapted to three different furnace applications for the client. The first (12 kV or 17.5 kV) has already been commissioned and a second slag cleaning application is being finalised. The third 33 kV solution is pending the final installation of panels. “We have provided three different solutions for three different areas of the plant,” Delport explains.
The work was done when the facility was decommissioned in line with the platinum miner’s furnace rebuild programme. While the furnace was being upgraded, it was decided to refurbish the substation as well. In parallel with this programme, two substations at Polokwane were also refurbished. “Obviously, the furnace rebuild had a tight timeframe and we had to carry out a lot of work during that limited period. We had one service team on-site running all three of the installations simultaneously,” Delport says.
Commenting on the technology applied, he adds that the PWC600 was designed originally for capacitive back switching. Prior to it being upgraded to switch single-phase transformers or power transformers, ABB was already using it for this application.
A third-party engineering house was appointed to carry out the initial investigation on the relay and the intended application, whereafter it was integrated successfully with ABB’s VD4 breakers. Two different solutions were applied: a VD4 P standard uniform breaker and a VD4 AF furnace-specific breaker was used on the 33 kV application.
“Just to get to where we are now was quite a challenge,” says van Zyl. “This is the first time this combination of products has been used for this particular solution.” Several global ABB product managers were also involved. “We shared our design and information so ABB globally could understand what we were doing and how we were applying it.”
As well as resolving the issue of nuisance tripping, another major benefit is the increased life expectancy of the equipment. “This is a solution that 100% suits the customer’s requirements. It is a testament to ABB’s flexibility in being able to assist its customers. There was a lot of upfront investigation and alignment between the customer, ABB and the EPC contractor that worked on the project,” Delport highlights.
“The plant personnel are getting used to the solution and are happy with its performance to date. They are relying quite heavily on the functionality it is providing.” He adds that the solution is now also being rolled out generally at another industrial company in Zimbabwe looking for the same level of technical capability. “A number of furnace operations are being built around what we have achieved in this first case,” says Delport.
Van Zyl adds: “We have to keep up with technology and with our customers’ requirements. They are keen to see what kinds of solutions we can put on the table. In this case, working with the consulting engineer, various subcontractors and the global ABB engineering team, ABB ELDS in South Africa pulled these installations together successfully.”
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