Sentryum AC Uninterruptible Power Supply

10-20kVA Single & Three Phase Output

The Sentryum series is a transformer-free UPS available in 10-15-20 kVA/kW models with three-phase/single-phase input and singlephase output, and 10-15-20 kVA/kW models with three-phase input and output.Sentryum provides the solution to installation problems in systems where the power supply has limited power available, when the UPS is supported by a generator or where there are compatibility problems with loads that generate harmonic currents.

Available in 10-15-20 kVA versions, the Sentryum improves on our popular Multi Sentry (MST) series and has been developed following extensive customer feedback. It is much easier and more cost-effective to maintain thanks to its fewer components and connectors.

The S3T redefines the concept of flexible power protection by offering three different cabinet sizes to meet the varied needs of small data centres and mission-critical applications:

Compact (CPT) 

  • Footprint less than 0.25m2 and volume of 0.17m3
  • 280mm x 840mm x 700mm (W x D x H)
  • 1 internal battery string
  • Specifically designed for extremely restricted spaces

Active (ACT) 

  • Footprint less than 0.35m2 and volume of 0.33m3
  • 380mm x 850mm x 1025mm (W x D x H)
  • 1 or 2 internal battery strings

Xtend (XTD) 

  • Footprint less than 0.4m2 and volume of 0.5m2
  • 440mm x 840mm x 1320mm (W x D x H)
  • Up to 3 internal battery strings in a single cabinet
  • Option to add isolation transformer
  • Can upgrade enclosure protection from IP20 or IP21 to IP31

High power availability

Sentryum’s fully rated design delivers full power (kVA=kW) regardless of the load power factor or operating temperature (full rated power is available up to 40 °C). Furthermore, Sentryum’s advanced digital control makes it possible to deliver up 250% inverter current for 200 msec and 150% for 300 msec. The high overcurrent availability enables the system to deal with sudden peak loads (without static bypass intervention) and provide the short circuit current if required during operation on battery. The innovative input stage design provides extremely high battery recharging current, whilst at the same time an energy efficient conversion process during battery operation to reduce the power wasted and to increase the autonomy time compared to legacy DC/AC converters.

Smart Battery Management

Proper battery care is critical to ensure the correct operation of the UPS during emergency conditions. The Riello UPS Smart  Battery Management consists of a series  of features and capabilities to optimise battery management and obtain the best
performance and operating life possible. Battery recharging: Sentryum is suitable for  use with conventional hermetically sealed lead-acid (VRLA), AGM and GEL batteries,Open Vent and Nickel Cadmium batteries.Sentryum is also compatible with ultimate alternative backup power sources such as LiIon batteries and Supercapacitors.

Superior battery charging current availabilityie up to 20 Amperes for the 20 kVA/kW power range, meaning that the Sentryum can be utilised within any extended battery autonomy application.Depending on the battery type, different charging methods are available:

  • One-level voltage recharge, typically used for widely available VRLA AGM batteries
  • Two-level voltage recharge according to IU specification
  • Cyclical recharge system to reduce electrolyte consumption and lengthen the life of VRLA batteries

Recharge voltage compensation based on ambient temperature to prevent excessive battery charging or overheating. Battery tests to diagnose in advance any reduction in performance or problems with the batteries. Deep discharge protection: during extended low-load discharges, the end-of-discharge voltage is increased – as recommended by battery manufacturers – to prevent damage or reduced battery performance. Ripple current: recharge ripple current (residual AC component at low frequency) is one of the main causes of reduced reliability and battery life. Using a high frequency battery charger, Sentryum reduces this value to negligible levels, prolonging battery life and maintaining high performance over a long period of time.
Wide voltage range: the rectifier is designed to operate within a wide input voltage range (up to -40% at half load), reducing the need for battery discharge and thus helping to extend battery life.

Maximum reliability and availability

Distributed parallel configuration of up to 8 units per redundant (N+1) or power parallel system grants exceptional expandability. The UPS continue to operate in parallel even if the connection cable is interrupted (Closed Loop).
Advanced technology and use of high performance components, allows Sentryum to provide exceptional performances and utmost reliability:

  • The smallest overall footprint is only 0.35 sqm for Sentryum 20 kVA/kW with two strings of 40 battery blocks
  • The input power stage (IGBT rectifier) ensures an input power factor close to 1 with extremely low current distortion, avoiding the need for bulky and expensive filters
  • Unity output power factor Sentryum makes it suitable to any data centre application ensuring full power availability without downgrading no matter what the load power factor range (typically from 0.9 lagging to 0.9 leading)
  • Extremely low output THDV under any circumstances provides a perfect sinewave and therefore a reliable power supply for the load preventing and disturbances from affecting the network users.
  • More active power than a traditional UPS, guaranteeing a greater margin when sizing UPS for potential future load increases.
  • More energy to face sudden load increase or clear output short circuits due to appliance failures downstream.
  • Smart ventilation principle, Sentryum manages the fan speed and airflow in accordance with the room temperature and load level. This preserves the lifespan of the fans, whilst at the same time reduces noise levels and the overall power consumption due to unnecessary UPS ventilation.Furthermore, the overall UPS high efficiency reduces the losses and therefore the need for high levels of ventilation compared to older legacy UPS. In addition, this results in a decrease in the overall noise level at the nominal load and a reduction in the number of fans required, which significantly benefits the operating and maintenance costs.


With its flexible range of three solutions, configuration, performance, accessories and options, Sentryum is suitable for use in a wide range of applications:

  • Suitable for powering capacitive loads, such as blade servers, without any reduction in active power from 0.9 lead to 0.9 lag
  • ON LINE, ECO, SMART ACTIVE and STANDBY Off operating Modes – compatible with centralised power systems (CSS) applications
  • Frequency Converter Mode
  • Cold Start to switch on the UPS even when there is no mains power present
  • S3T 20 XTEND version: cabinet (440 x 850 x 1320 mm WxDxH) for optimised solutions when medium to long-term runtimes are required (up to one hour back up time for a 20 kVA/kW at typical load rate
  • Parallel configuration up to 8 units for three phase version
  • Optional temperature sensor for external battery cabinets, to assist recharge voltage compensation
  • High power battery chargers to optimise charge time in the event of long runtimes
  • Dual input mains power supply (not applicable on Compact, optional for Active, standard on Xtend version)
  • Mechanical fitting for a higher rating of IP protection either IP21 or IP31 on Xtend version
  • Compatibility with alternative backup energy sources rather than lead batteries (NiCd or Li-ion batteries or supercapacitors)
  • Different sized battery cabinets and capacities, for extended runtimes

Advanced communications

The S3T incorporates USB, RS232, and RJ10 ports, plus various slots to insert parallel and network communications cards. It is compatible with the full range of Riello UPS networking and UPS management software, including PowerShield3 and PowerNetGuard.

Series Table

Model Nominal Power (kVA) Nominal Input Voltage Output Voltage Output Number of Phases
SRM-CPT-ACT-XTD 10 BAT 10 380 / 400 / 415 three-phase + N
220 / 230 / 240 single-phase + N
220 / 230 / 240 single-phase + N (selectable) 1 + N
SRM-CPT-ACT-XTD 15 BAT 15 380 / 400 / 415 three-phase + N
220 / 230 / 240 single-phase + N
220 / 230 / 240 single-phase + N (selectable) 1 + N
SRM-CPT-ACT-XTD 20 BAT 20 380 / 400 / 415 three-phase + N
220 / 230 / 240 single-phase + N
220 / 230 / 240 single-phase + N (selectable) 1 + N
S3T-CPT-ACT-XTD 10 BAT 10 380 / 400 / 415 three-phase + N 380 / 400 / 415 three-phase + N (selectable) 3 + N
S3T-CPT-ACT-XTD 15 BAT 15 380 / 400 / 415 three-phase + N 380 / 400 / 415 three-phase + N (selectable) 3 + N
S3T-CPT-ACT-XTD 20 BAT 20 380 / 400 / 415 three-phase + N 380 / 400 / 415 three-phase + N (selectable) 3 + N

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