Product Description

Delivering outstanding performance at lower operating costs, the Master HE 250 from Specialist Power Systems is the perfect option for protecting mission-critical and industrial loads.

Up to 8 units can be installed in parallel to increase capacity or redundancy depending on the requirements. Using advanced online double conversion technologies, the Master HE is designed to protect data centres, IT and telecommunications networks, electro-medical devices, security systems, and industrial loads from blackouts and other damaging power disturbances.

Its IGBT-based rectifier produces far greater operational efficiency compared against the more conventional thyristor-based systems. In online mode, operational efficiency of 95.5% stands comparison with transformerless UPS power supplies.

Providing a unity power factor, it includes an output isolation transformer which offers better load protection, enables the UPS to be supplied from two independent lines, and guarantees higher immunity to any harmonics generated by the load.

Users can manually select or programme a variety of operating modes that improve system performance or efficiency:

  • Online Mode: maximum load protection and output voltage quality
  • Eco Mode: maximum efficiency up to 99% as the load is powered by the mains only
  • Smart Active Mode: UPS automatically decides what mode to run depending on the stability of the incoming supply
  • Standby Off Mode: for loads such as emergency lighting, which don’t need power until the mains supply fails
  • Frequency Converter Mode: enables the output frequency to be different to the UPS input frequency

The Master HE can be configured in a variety of ways, such as:

  • UPS Group Synchroniser (UGS): enables 2 or more non-parallel UPS devices to remain synchronised even during mains power failure. UGS also enables a Riello UPS to synchronise with another independent power source, even one with a different power rating.
  • Parallel Systems Joiner (PSJ): this connects 2 groups of UPS in parallel using a power coupling switch. If one of the UPS in the group fails, it is automatically excluded and the PSJ links the remaining UPS to the other group through an external bypass.

Quick maintenance and service access is available thanks to a removable front panel, which also incorporates an advanced LCD display panel showcasing UPS status and alarms, input and output voltage, battery levels, and other measurements that can be used to monitor performance and calculate data centre power usage effectiveness (PUE).

The Master HE range all integrate with Riello UPS’s full suite of monitoring and networking communications software such as PowerNetGuard and PowerShield3.       

Specialist Power Systems are an approved sales partner to Riello UPS in the UK with expert technical knowledge. Call us on 01234 851155 to discuss your requirements and how we can help you find the right product and support.

Product Specification

Part No

MHE 250

Capacity (VA / kVA)

250 kVA

Maximum Output (Watts)

250000 Watts

Form Factor




Run Time


Warranty Length

3 Years

Battery Type

VRLA AGM / GEL; NiCd; Supercaps; Li-ion; Flywheels









3 years

Optional Accessories

Here at Specialist Power Systems we offer a wide range of manufacturer specific accessories from a UPS Network Card through to an External Maintenance Bypass Switch. Please get in touch so we can ensure you get exactly what you need to stay protected.

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For more information, please call us on +44 (0) 1234 851155 or send us a message below.

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