Unique characteristics of Turbocor compressors mean correct maintenance is vital, say Roberto Mallozzi and Ken Strong.

The principles behind the Turbocor compressor are completely different to conventional compressor systems. The high performance technology has proved to be exceptionally reliable, with an oil-less design and reduced number of moving parts.

But when it needs servicing it is vital to use trained specialists or it can result in very serious problems. The compressor is based on a two-stage centrifugal impeller and spindle, which is 'levitated' in a powered magnetic bearing. A DC inverter powers the motor, and the system is under the control of a sophisticated onboard microprocessor.

In the same way that it would be unwise to employ a regular garage mechanic in the pits for an F1 championship, it is risky and potentially dangerous to let an untrained service engineer loose on a Turbocor. This has unfortunately been borne out by experience, with instances where field engineers or enthusiastic end users untrained in the particular technology have tried to tackle Turbocor servicing. At worst, this has resulted in catastrophic damage to compressors and put the chiller out of action.

The principles behind the technology are completely different from conventional compression systems. On a mechanical level, with its single moving part - the shaft and related impellers - the Turbocor appears deceptively simple. However, related support systems, particularly the electronics, are highly sophisticated. It is genuinely 'space-age technology'. To handle it safely and effectively requires specialist training.

For example, a key requirement is to ensure that electronic components contained within Turbocor are protected from moisture. Because the electronic systems are critical to Turbocor's performance, this aspect is part of a regular annual service that needs to be carried out according to a set procedure.

The Turbocor is also equipped with a bank of high-power capacitors, mounted on the side of the compressor case. These are provided as back-up electrical power in the event of mains power failure, to keep the unit operating until it can be brought to a controlled stop.
Due to normal deterioration over time, it is necessary to replace the capacitors after 10 years of service. But the enormous voltage presents serious health and safety issues in handling these components, risking serious injury in untrained hands.

The Turbocor incorporates an onboard data collection, management and diagnostic system, which shows COPs, capacity, output and any faults or alarms over the period since the last service. But to evaluate this wealth of data effectively requires training in the operating and diagnostic system. The interface can also be used to make adjustments to system parameters, which, altered without proper knowledge, risks creating potentially unsafe performance conditions. In the case of the Turbomiser chiller, the compressor controls are integrated with the overall chiller controls in order to optimise performance for a given set of conditions.

Again, the necessary fine adjustments to seasonally tune the machine to ambient conditions requires knowledge of both the Turbocor operating system and the over-arching chiller controls to ensure the correct integration and tuning to design conditions.

When it comes to leak detection, field engineers cannot rely on the conventional approach of spotting oil leaks around the system as a clue to possible points of refrigerant leakage - because the Turbocor's design is oil-less. Therefore correct use of electronic or ultrasonic refrigerant leak detection is needed when servicing the machine.

Turbocor-based chillers are bound to grow in popularity as energy prices rise and energy efficiency becomes paramount, so it is vital that the servicing is carried out by trained service engineers. The safety of the servicing engineer and the security of the process or building being cooled depend on it.

Roberto Malozzi is managing director of Klima-Therm and Ken Strong is managing director of Cool-Therm

RAC Magazine October 2011