Case Study
Water Pumping

The freshwater pumping station was constructed in the mid-1970s and consisted of dual vertical turbine pumps, driven by 11kV Wound rotor motors.

While some instrumentation, control, and ancillary electrical systems had undergone upgrades in the period since the pumping station was commissioned, the bulk of the electrical equipment including the motors and starters were part of the original infrastructure installed over 40 years ago.

This project's scope was to increase pumping station reliability by ensuring the operational life of electrical system assets was extended for the next 20 years.

The main aims were to

1. 1. Optimise system operation through the integration of improved technologies to enhance pumping station monitoring and control and reduce power usage.
2. 2. Reduced risk of supply interruptions caused by unplanned pumping station outages due to aging equipment.
3. 3. Eliminate WHS risks where possible by providing equipment and electrical installations that comply with current statutory requirements

The existing wound rotor motors with stepped resistor starters were to be replaced with new Toshiba 4000kW 16P 11kV asynchronous squirrel cage induction motors and TMdrive MVG2 5500kVA 11kV(in)/ 11kV(out) Inverter which were not only providing a soft start, but also provide speed control, and pumping station flow control.

Some challenges regarding this project were:

1. 1. The motors had been in situ since their original installation, and information regarding the interface required measuring which meant the pumps needed to come off-line and be removed to take detailed measurements of each motor with attention to the forged shaft coupling, flange mating, and the pump flywheel itself for the precision pins.
2. 2. Size of the switch room allocated for the VSD drives was fixed as the building could not be altered due to its design and heritage.
3. 3. Noise level of having 2 x drives within a small switch room within 80dB(A) sound pressure level.
4. 4. Transport to the site taking into consideration small windy roads and overhead power lines which required a road survey to determine allowable routes and limits.

By the early stages of the project, the existing motors were removed and with engineers from both Australia and Japan, all key mounting dimensions were measured and recorded. A shaft coupling template was also prepared for each motor taking into account variances between both machines as the customer no longer had the original coupling templates.

The Toshiba MVG2 inverter was selected to meet customer overload specifications whilst being compact to fit within the customer switch room.

Safety was considered in the design of the MVG2 inverter which included isolator and earth switches fitted to the input panel complete with a viewing window. The fortress locking system was incorporated and integrated with a site safety system.

The Inverters were witness tested in Fuchu Japan exceeding customers’ expectations.
 

In partnership with our local transport company, a road survey was conducted from the discharge port to the site. Permits were then prepared to allow for smooth and uninterrupted travel to the site. The road survey also provided details for the motor factory to consider the packing requirements which allowed for the delivery truck to reverse into the pump station for unloading by overhead crane.

Toshiba provided site supervision and commissioning services throughout various aspects of the project including measuring up of the existing motors, assisting with the pump flywheel machining off-site during the pump overhaul process, and also commissioning the motor and drive.