MTU DRUPS (Diesel Rotary UPS)

Uninterruptible Power Supplies, with battery or flywheel back-up, provide a few seconds to a few minutes, or up to a couple of hours, of backup power to immediately replace power from the main in case of failure. While these short periods of time can give facilities time for an external generator to start and come online, or time for personnel to perform proper equipment shutdowns, UPS are only suitable for short periods of time and cannot support long duration power outages without transferring the load to a separate generator back-up system.

Diesel rotary uninterruptible power supply devices (DRUPS) combine the functionality of a battery or flywheel UPS and a diesel generator for long term uninterrupted power without a transfer. A DRUPS can have enough fuel to power the load for days or even weeks in the event of failure of the mains electricity supply.

MTU DRUPS provide a dynamic uninterruptible power supply through kinetic energy. MTU, a Rolls Royce Company, manufactures these flywheel-based back up power systems that meet the need for specific power, footprint, and sustainability, and provide a competitive alternative to static UPS systems.

This dynamic UPS technology is based on kinetic energy and consists of a diesel engine, synchronous machine, accu kinetic energy module, and clutch mechanism. Floor-standing control (COP) and power (POP) panels complete the system. These battery-free UPS systems ensure reliable and environmentally friendly uninterruptible electrical power and provide power conditioning. Without the need for batteries, the system offers the highest power density (kW/m²) in the industry with high system efficiency in conditioning mode, low total cost of ownership, small footprint, scalable solutions, and a compact design.

MTU DRUPS Features 

• Lower TCO – At medium and higher power ratings, they are more cost-effective, reducing consumable electricity cost and maintenance.
• Smaller footprint – Its component count and monobloc structure give it a compact design, reducing its footprint to 40% of an equivalently rated static UPS system – making it the smallest in the market. This reduces building construction costs and increases space for production and revenue generating purposes.
• Units up to 3000 kVA – with ratings between 150 kVA/120 kW to 3000 kVA/2160 kW offered at 50 Hz and 60 Hz frequencies. The current-carrying capability of electronic components does not limit these units.
• Optimal sustainability – static UPS systems require heavy batteries and generate chemical waste. These units are immediately available to generate power until the MTU diesel engine is activated.
• Medium voltage systems – the perfect solution for medium voltage critical loads or when more considerable distribution distances need to be covered. In both cases, the installation cost will decrease on low voltage cabling as the quantity required will be smaller.

How does a DRUPS system work?  
The MTU technology consists of a constantly rotating kinetic energy storage unit with flywheel, an MTU diesel engine and an alternator which, depending on the operating mode, also operates as an electric synchronous motor with its preferred compensation characteristics. A special control unit with the accompanying switchgear and a choke that acts as a line filter, complete the system. Power from the public grid drives the synchronous alternator, which acts as an electric motor in this operating mode. This in turn drives the flywheel in the kinetic energy storage unit which weighs tons and is designed as an electric machine with double rotor system. This serves as the “energy accu” which stores energy and makes it available in the unlucky event of a power outage.  

What happens when the primary power source fails?
If the public power grid fails, the systems acts immediately and without interruption because it is already in operation anyway. Part of the energy stored in the flywheel is used to drive the generator, that starts producing electrical power. Meanwhile, another part of the stored rotational energy is used to facilitate very fast start-up of the diesel engine. Within the shortest possible time the engine accelerates to its rated power output and can now start producing electrical power via the generator and stabilize the flywheel. This naturally happens without any gap or interruption – hence the name “Uninterruptible Power Supply”.    

Is another battery required?
No. No battery is required because the energy in the kinetic energy storage unit can be made available immediately for generating power until the MTU diesel engine comes on-line.