Extended product life and energy savings in the demanding world of stone crushing

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Extended product life and energy savings are being achieved in the demanding environment of industrial rock crushing thanks to the introduction of Invertek Drives Optidrive P2 variable frequency drive motor control.

An Italian aggregate company was using a jaw crusher driven by a soft starter to break down river stones. This limited the amount of control of the speed of the crusher and the size of the particles being broken down. Specifically, the lack of high torque at start-up was a critical factor in the need to replace the system.

Invertek Drives Italia was brought in to resolve the situation by retrofitting Optidrive VFD technology.

Alessandro Venier, Field Application Engineer, explains: “Our client provides a range of primary, secondary, and tertiary crushers for reducing and refining aggregate material through compression, impact, and attrition or shear force.

“In this case, they had a jaw crusher for primary crushing. The machine has two jaws in a V-shape, with one stationary and the other swinging back and forth against the other to create a compressive force for breaking down the material.

“Because the main motor on the crusher was driven by a soft starter, there was little control over the speed of the motor and the movement of the jaw. With a high-torque starting phase required, the soft starter was simply ineffective and this was not acceptable.”

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Accurate motor speed control for different material types and size

He added: “They also needed to control the rotation speed depending on the type and quantity of the material being crushed.”

Alessandro added there was also a lack of control of the power supply system when the rated current was exceeded. Starting speed needed to be smooth to minimise any stress on the machine and to eliminate high starting currents.

Mauro Grassivaro Area Manager at Invertek Drives Italia said: “A high-performance Optidrive P2 VFD was identified for the application with an IP55 enclosure. This allowed it to be cabinet mounted close to the crusher for easy operator control of the speed while being robust enough for the harsh environment it would be operating in."

Specifically, a Size 8 110kW with 400V input P2 drive was installed and commissioned to control the 400V, 3 Phase, 90kW motor.

The Optidrive P2 is one of the most powerful VFDs in its class. It combines high performance with ease of use and can handle 150% overload for 60 seconds.

Immediate results with required ramp start at full rated torque

“The results were instant with the P2 immediately optimising the system,” said Alessandro. “It provided the required ramp start with full rated torque of the motor - something the client demanded. Additionally, coast to stop and spin start was enabled.

“This saves energy and also means braking resistors did not have to be applied. The spin start avoids wasting time and production waiting for the flywheel to stop before restarting.”

He added: “The customer has tested the machine with all types of stone and maximum load in the feeder and everything worked perfectly.”

Key benefits for the customer, in addition to energy savings, have been the elimination of mechanical stress on the belts and on the machine structure which reduces wear and tear, downtime and associate costs, in addition to extending its lifetime.

“Additionally, this has increased productivity and eliminated the number of machine stops due to material blockage,” said Alessandro. “The customer has already ordered more P2s for other crushers they’re using.”

The Optidrive P2 is available in IP20, IP55 and IP66 / NEMA 4X enclosures; single and three-phase input of between 200v to 600v, 0.75kW to 250kW and 1HP to 350HP. It supports all motor types, including IM, PM, BLDC and SynRM.

Its built-in EMC filter and integral brake transistor also saves cost and time for installation.

More information about the Optidrive P2 VFD range can be found at www.invertekdrives.com/variable-frequency-drives/optidrive-p2

For more media information, contact:
Owain Betts, PR and Communications Manager
t: +44 (0)1938 558 253
m: +44 (0)7483 072 739
e: Owain.Betts@shi-g.com