The Rapidbatch 120 is a mobile concrete batching plant, produced by Rapid International .It offers a batching plant which is quick to deliver and commission. The Rapidbatch 120 is typically specified for a 500 kVA generator. The plant has 26 different electric motors varying in size from the 6 off 370 W additive pumps up to the 2 off 55 kW mixer motors.
Figure 1. The JCB Power 300 kVA generator, with the PUNCH Power 200 behind (in green)
The Teesworks is a vast site, located near Redcar is the North East of England. It plans to become a freeport, as well as the “carbon capture capital” of the UK. To support the requirements of the extensive construction works, Heidelberg Materials (formerly Hanson) have deployed the Rapidbatch 120 to produce concrete for the site. In this case study, Sunbelt successfully downsized the 500 kVA generator to a 300kVA using the PUNCH Power 200 flywheel system from PUNCH Flybrid.
Applications such as this can be complex. There are 26 different motors of varying powers and with differing start types. The generator is sized to cope with peak load, but this can be hard to assess as different running programmes can result in different combinations of simultaneous motor starts. To confirm that the downsized generator will function for all programs, commissioning engineers from Pneutrol were on hand to set up simultaneous starts of several large motors, including the largest DOL motors. This case is beyond the normal operating parameters, and will ensure the system will work under all expected load conditions.
The 300 kVA generator was commissioned and connected to a large fuel tank and earth leakage was set correctly for the flywheel (> 300 mA). The PUNCH Power 200 was set up with CT clamps connected and in power capping mode with a limit of 200 kW. Power factor
correction mode was enabled with a target of 0.95.
During the tests it was observed that the power factor was momentarily very low, and the flywheel was providing almost all reactive power to maintain grid stability. This was due to the large, multiple starts of direct online motors occurring as part of the test. Despite this, the power system functioned as expected and was handed over to the site team.
Figure 2. The power system being handed over to the site team following successful commissioning
The reduced generator size we estimate will save 275 litres of diesel per week. On top of the savings from hiring a smaller generator. As such the site should see CO2 emissions cut by around 37 tonnes per year. PUNCH Flybrid would like to thank the teams from Teesport, Rapid International, Heidelberg Materials, Pneutrol, Youngs Electrical and Sunbelt Rentals UK for making this test happen.