Sasol Mining selected the flexible ABB Relion® protection relays for a new substation at the Syferfontein mine in South Africa. The scope of functionality, event and fault recording capabilities, reduced footprint, and cost reductions were key factors in the decision.
ABB’s UniGear switchgear line-up at the Syferfontein substation.
Sasol Mining, part of South African integrated energy and chemical company Sasol, undertakes the company’s coal mining operations. It operates six coal mines that supply about 40 million tons of thermal coal feedstock per year. At the company’s largest colliery, the Syferfontein mine in the Secunda area, Sasol Mining identified that an existing ventilation shaft was not sufficient to ensure the required ventilation of the mining zone. To ensure uninterrupted power supply to a new ventilation shaft, it needed a new substation.
In underground mining, ventilation systems are critical to ensure safe working conditions. Ventilation systems provide clean air, dissipate and remove dust as well as natural and machine exhaust gases, and provide cooling for personnel and machinery. The systems need to run continuously 24 hours a day, throughout the year, which means uninterrupted power supply is a key requirement. The energy demand is significant and ventilation systems are one of the biggest users of power in underground mines, accounting for as much as 50% percent of energy use.
For the new substation that feeds the new ventilation shaft at the Syferfontein mine, Sasol Mining chose a protection and control solution with ABB’s Relion® relays from the product family’s 615 and 620 series, as well as the all-in-one protection relay REX640, to be installed in the medium voltage switchgear. This is the first installation with ABB’s Relion® protection and control relays for Sasol Mining.
“A key consideration for us when deciding in favour of the Relion® relays was that they offer all the functionality we need,” said Divesh Ramasur, Senior Electrical Engineer at Sasol Mining. “They are also flexible and offer a range of event and fault recording capabilities.”
Sasol Mining also chose the protection and control relays for the circuit breaker control functions they provide and because they have arc flash protection embedded for increased safety. They include the simpler GOOSE (Generic Object-Oriented Substation Event) protocol and all have the R/L (remote/local) switch available on the relay faceplate for easier operation.
Additionally, the customer chose Relion® 620 series relays for motor protection. The relays offer stall protection functionality and thermal overload protection, considering the actual starting time of the motor.
The installation of Relion® relays has enabled cost reductions and a reduced switchgear footprint. “With REX640 we can use only one relay for transformer protection, whereas previously we have had to use a number of different relays to achieve the same level of protection,” said Ramasur. “The REX640 relay incorporates various transformer protection functions: low impedance differential protection, low impedance restricted earth-fault protection, sensitive earth fault protection, and tap changer control, for example, are all integrated into the relay. It also has multiple binary inputs and outputs and can incorporate analogue inputs, too.”
The footprint of the switchgear was reduced as there was no need to install three different relays to obtain the same functionality. The built-in R/L switch and master trip relay obviated the need to install separate switches on the panel. And overall a cost reduction of about 25% was achieved.
Further, with the Relion® 615 series (REF615) and 620 series (REM620) protection relays in the substation, the customer estimates the total costs were reduced by 10%.
Sasol is involved in energy, chemicals and synfuels and ABB and Sasol have a long business relationship. Sasol has previously used Relion® relays at its Secunda and Sasolburg petrochemical plants, proving their suitability for operation in harsh environments. To ensure optimal performance, Sasol Mining chose an additional layer of protection in conformal coating for the relays. Adding a conformal coating to the printed wired boards (PWBs) protects the electronic circuits in particularly tough environmental conditions, such as in underground mining.
For more information visit: go.abb/digitalsubstations.
