The Hitzinger Rotary Diesel UPS system provides the optimum solution for mission critical applications that require a source of uninterruptable power supply. The NBDD system, with rigid steel flywheel energy storage device, provides guaranteed tolerances on the consumer with +/-5% frequency variation (See NBDK for +/-1% IT Grade Power). The NBDD system is the perfect solution for industrial applications, airport lighting systems, stadiums and other mission critical environments.

The Hitzinger Rotary Diesel UPS system is made up of four main components; The flywheel which is directly mounted to the alternator, the diesel engine and the coupling choke. During the stand-by operation, the system provides a reliable source of clean power and conditions the mains input to ensure; automatic power factor correction (0.98>unity), Harmonic suppression (<2% to Comply with G5/4) and Input load levelling irrespective of 100% unbalanced load. As an alternative to the traditional static UPS with battery energy store, the DRUPS provides an unrivalled level of reliability, with a MTBF of over 1,000,000+hrs.


During stand-by, the flywheel is accelerated to full speed (Also referred to as charged) and runs continuously together with the alternator to provide mains power conditioning. In-case of mains failure, the energy stored within the flywheel is used to maintain the speed of the alternator and provides a sufficient bridge until the diesel engine has accelerated to a speed of ~800rpm. At which point, the electromagnetic clutch will engage and the diesel engine will be brought up to synchronous speed to become the main drive of the alternator and provide guaranteed power for the longer duration.

Only when the flywheel has become fully charged and the mains is available, will the rotary Diesel UPS system synchronous back to the mains ready for another interruption.

Coupling Choke

The coupling choke connects the incoming grid with the UPS output supply. This setup provides conditioning of the the mains to within tolerance together with power factor correction and harmonic suppression.

The special design of the choke provides a high degree of de-coupling in both directions between the input and the output. The Coupling choke provides:

In the event of input short circuit the current flow towards the grid network is limited by the choke to < 200 % I nominal until the input is disconnected. During this transient the current feed back to the mains is wholly reactive, ensuring all the kinetic stored energy can be fully utilised for the critical load.

Technical data


Power classes


If you require a Technical Specification, please send us an Email (Contact Us) detailing your requirements. and we can can send the appropriate documents for your review


Technical highlights