UNIBLOCK UBTD+ Rotary Diesel UPS from 500 kW up to 40 MW

Rotary Diesel UPS from 500 kW up to 40 MW

The UBTD+ is unlike any other UPS. Consisting of a special combination of proprietary motorgenerator and choke, this UPS provides a very simple and highly reliable uninterruptible power solution with exceptionally high efficiencies. The technology employed provides an extremely robust, small footprint, high power solution designed to give over 20 years of dependable operation.

Introducing the UNIBLOCK™ UBTD+

Piller’s rotary Diesel UPS systems of the patented UNIBLOCK type represent the most efficient and reliable power supply combination for critical applications.

The design flexibility of the UBTD+ is unique for a UPS system, it can be used to address low and medium voltage applications, cooling can be by air or chilled water, critical and emergency supplies can be isolated or combined in a single distribution system. Diesel start delay can be varied from seconds to minutes and multiple engine designs can be accommodated.
The UNIBLOCK UBTD+ Diesel Rotary UPS combines all the benefits of a rotary UPS with a Diesel engine in one integrated unit and can work with all brands of Diesel engine used for UPS applications. The UBTD+ is available either with flywheel or battery backed ride-through.

Single machines sized 500 kW up to 2700 kW can be paralleled in standard or IP-Bus configurations for redundancy and added capacity.

Click here to view the Rotary Diesel UPS Simulator


  • Rotary UPS from 500 kW up to 40 MW
  • Highest reliability
  • Highest efficiency, up to 97%
  • Total Design Flexibility
  • Medium voltage option available
  • Water cooling available using building chilled water
  • Battery- or flywheel backed versions
  • More than 3 times longer bridging time from Piller kinetic energy storage than with any other commercially available flywheel system
  • Redundant on-board power supplies
  • Leading and lagging output power factor without derating
  • 100% load step capability
  • Inherent fault clearing ability for short circuit faults without bypass
  • Virtual unity input power factor
  • 99% input/output harmonic isolation

Principle of Operation

The UNIBLOCK™ UBTD+ Diesel Rotary UPS combines all the benefits of a rotary UPS with a diesel engine in one integrated unit. The system consists of the UNIBLOCK™ motorgenerator (MG) connected via a free wheel clutch to a diesel engine, all mounted on a single short base frame. The load is normally fed via an isolating and coupling choke connected to the utility supply. The choke has a second tapped connection to the motor-generator. In the event of short interruptions or complete outages, the load is supported initially by a ride-through source which can be either a conventional battery system or a Piller POWERBRIDGE™ electrically-coupled kinetic energy store – alternatives unique to the Piller design and providing the longest ride-through times available in the market. With the load safely supported, the diesel engine is then given a command to start. Once up to speed, the system hands over the long-term support of the load to the engine by seamlessly engaging the clutch.

The UNIBLOCK™ Motor-Generator

At the heart of every Piller Rotary UPS lies the pre-eminent UNIBLOCK™ synchronous motorgenerator with its unique low-distortion, high fault-clearing characteristics. The UNIBLOCK™ machine’s motor and generator windings share a common stator and a single brushless rotor to provide a highly compact double winding machine with unique electrical characteristics. The combination of special electric steel and combined stator windings gives rise to a machine with exceptionally high efficiency whilst exhibiting the sub-transient reactance required for low harmonic distortion and high fault clearing capacity. An incorporated damper cage reduces harmonics and the standard bearing design ensures long operational performance with minimal maintenance. The machine is manufactured and balanced by hand at the Piller factory to ensure extremely long service life.

System Reliability

A design free of power capacitors eliminates the common failure component generally found in static UPS. The durable rotary machine technology is far less sensitive to damage from overload and other electrical disturbances and uses no brushes, slip rings or complex bearing arrangements. The power electronics employ rugged semiconductor technology with no need for internal device paralleling or multiple power capacitors. Bypass operation is not required for any aspect of the UPS function and in most cases, electric cooling fans are eliminated by using the impeller of the UNIBLOCK™ machine for the system cooling. All of these factors combine to provide a UPS which exhibits a level of reliability that cannot be matched by other technologies. 

UNIBLOCK™ UBTD+ features
Single machines sized 500kW up to 2700kW
Paralleling up to 40MW
Higher reliability than other technologies
Highest partial and full load efficiencies with energy store connected
Total design flexibility
Medium and low voltage options
Battery or kinetic energy store versions
Typically 3 times longer bridging time from the POWERBRIDGE™ compared with other UPS
Fastest recharge time with POWERBRIDGE™
Wide leading and lagging load power factor without de-rating
Inherent fault clearing ability for downstream short circuits
Virtual unity input power factor
99% input/output harmonic isolation
Small footprint and high power density
Simple maintenance requirements
File Name Size
Piller UBTD+ Product Brochure 921.57 KB Download