AC drives keep Chinese cranes working

Control Techniques is supplying 160 AC variable speed drives for cranes in Xiamen Haicang Port in Fujian Province in the south of China.

Control Techniques is providing large AC variable speed drives for cranes in several Chinese ports.

The latest of these is a huge project for around 160 drives in Xiamen Haicang Port in Fujian Province in the south of the country.

The port is now owned by Hutchisons Ports Holding (Hong Kong), the world's largest port operator, who is acquiring many of China's busiest ports.

Xiamen is ranked number seven in China with a throughput of 3.34 million TEU in 2005, an increase of 16.4% on the previous year.

Control Techniques, part of Emerson Industrial Automation, with a well-established drive centre in Shanghai and a further applications centre in Beijing, has been working closely with a number of the major port crane OEMs in China.

These include ZPMC in Shanghai, the world's leader in AC cranes, SPMP in Shanghai, Changzhou GT, GangDi in Wuhan and Noell in Zhangzhou, providing AC drives for both new cranes and retrofits and DC drives primarily for retrofits in ship-to-shore (STS) and rubber-tire-gantry (RTG) port cranes.

"Our business in China started mainly with DC retrofits", says Control Techniques' Crane and Hoist Business Development Manager, Michael Nakulski.

"Over the last few years, we've supplied many DC drives for cranes from 10-40 tonnes in many Chinese ports".

"In these instances, generally the hoist and gantry shared one DC drive, the boom and trolley sharing another, with the Mentor II digital drives being fitted with a field current controller, a fieldbus adapter and running constant power hoisting control software for smooth anti-sway operation".

"A typical example is the DC retrofit of an STS crane at Qingdao Port, with a 450kW Mentor controlling the hoist and boom and a 125kW Mentor for the trolley and boom".

"It was eight years ago that Control Techniques achieved its first success in the AC drives arena with an STC crane, with active front end, supplied by ZPMC for Shanghai Longwu Port".

"Using a common DC Bus supply and full sine-wave four-quadrature energy-saving operation, the configuration was for hoist and gantry to share one drive - in this instance a 150kW Unidrive - with a second 150kW hoist motor drive synchronised in 'digital lock'".

"A second size-five Unidrive controlled the trolley (112kW) and boom (45kW) motion".

"ZPMC followed this up with an order for Control Techniques AC drives for a 1600 tonne float crane".

"Unidrives were supplied for the main hoist (2X480kW), the 210 and 110kW auxiliary hoists and the boom (2x480kW)".

"The crane operated with the main hoists in load sharing mode and communicated throughout using Profibus DP".

"Our design philosophy gives us major benefits in the port crane market", explains Michael Nakulsky.

"Our Unidrive SP range has a modular design with standard power modules that are produced in quantity to extremely exacting quality standards".

"There is no variation in build, with thousands being made every year, so the field reliability is the best in the market".

"From the customer's point of view, this means that modules are interchangeable".

"Few spares need to be carried (keeping costs down) and, in the rare event of a failure, the crane can continue at a reduced capacity to complete the task in hand, until a convenient moment when the module can be interchanged in a matter of minutes, with no programming required".

"Should the module be a 'master', setting up of parameters is as quick and easy as inserting a SmartCard".

"Everything is designed to minimise downtime and maximise port productivity".

The Unidrive SP range is packed with features to meet the variation in crane design and operation needs.

Wireless Ethernet gives connectivity to terminal management systems, internal load measurement helps determine optimum hoisting and travelling speeds to maximise throughput and Secure Disable (to EN954-1 category 3 or 4) gives absolute safety when undertaking maintenance.

An RFI filter is a standard fitment and options include connectivity to all major fieldbus protocols such as Profbus and DeviceNet, as well as a 48-96V DC battery back-up facility to return all equipment to safe and secure positions in the event of a supply failure.

Crane control has been refined over many years to meet the specific duties called for in different applications; anti-sway control, differential GPS control for RTG automated steering systems, and grab/hoist co-ordinated control and slew control to give operators greater "feel".

Operator control consoles and screens are designed for clear information and operator comfort and energy- saving functionality is a major benefit, particularly for cranes using diesel generator supplies.

The Control Techniques crane drives range encompasses global voltages up to 690V and ratings up to 1.5MW.

Harmonic reduction through sine-wave AC line regeneration produces significant energy saving.

Many thousands of drives have been supplied for container cranes - ship-to-shore, rubber-tire-gantry, rail-mounted-gantry and straddle carriers - for bulk handling - ship loaders and unloaders, grab unloaders, slewing grabs and barge-mounted grabs - and Cargo systems - single and double booms and Goliath overheads.

XICT, a joint venture with Hutchisons Port Holdings, is seen as one of the most important port developments in China and is poised for major growth.

Control Techniques' Drive Centre in Shanghai has a close working relationship with the port operators and can point to many major successes over the years, with upgrades of quayside cranes, both DC and AC, a sinewave regeneration on an STS crane, high-voltage cable reelers and upgrading of RTG cranes being just a few examples.

Currently, Control Techniques is about to commission over 160 modular Unidrive SP drives across two projects at the Xiamen International Container Terminal and one project at the Xiamen Hairun Container Terminal, the crane OEM being Shanghai Port Machinery Plant (SPMP).

The first of these, at the Xiamen Hairun Container Terminal comprises four sets of 20 Unidrive SPM AC drives for SPS cranes.

These are Post-Panama ship-to-shore containers rated at 65 tonnes with a boom height of 43m and a boom length of 63m.

The hoist has a no-load speed of 180m/min and a full load speed of 75m.

The trolley speed is 210m/min, the gantry speed is 45m/min and the boom duty cycle is seven minutes / single way.

Unidrive SP drives are responsible for all motor control operations.

The hoist section comprises two motors coupled together to a common gearbox.

In normal operation both motors will operate, one in speed loop, the second in torque mode, but, in an emergency either one can be operated individually.

The drives for the trolley and boom sections operate in closed loop speed control.

The gantry section comprises 16 motors, operating in parallel in open loop control.

The crane features constant power hoist control, a hoist position counter, additional hoist protection and hoist brake control.

The software tools required are included as part of the package, making commissioning straightforward.

It is simply a matter of plugging into any of the drives and the whole system can be viewed and set up.

The Control Techniques drive system provides full sinewave PWM rectification, with four-quadrant control to give maximum energy-saving.

In the event of any failure, the system can still operate at reduced power.

Each power stack can be tested independently before paralleling, additional units can be added later for greater power demand and an extra power stack can be connected to provide system redundancy.

As part of the same project, Control Techniques has also provided a 5.5kW Unidrive SP running a high-voltage cable reeler and a 30kW Unidrive SP operating two 7.5kW motors in parallel on the spreader cable reeler.

Two further sets of 26 drives have been supplied for two 65 tonnes ship-to-shore cranes for the Xiamen International Container Terminal - boom height 43m, boom length 63m, hoist speeds 180m/min, no load and 75m, full load.

Finally, six sets of seven drives have been supplied for rubber tire gantry container cranes at the Xiamen International Container Terminal.

Each is rated at 41.5 tonnes, with hoist speed at 55m/min, no load and 23m/min, full load.

The Unidrive SP modular drive is well suited for port crane applications, especially with regeneration.

The design meets all of the needs of both the crane builder - standard sizes, ease of programming and energy efficiency - and the user - with its exceptional reliability, flexibility in operation, ease of maintenance, safety, low spares requirement and energy saving operation.

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