The Riello UPS centralised by-pass (named MSB ) is available in four standard power ratings: 800, 1200, 2000 and 3000 kVA.Intermediate solutions within this range can be made, as well as solutions greater than 3000 kVA based on the requirements of the customer or application.The MSB centralised by-pass can be integrated with the Master MHT range; in fact it can be associated with up to 7 UPS modules in the range, obviously without static by-pass and associated by-pass line (named MHU ). Based on requirements, MSB can also be compatible with the MASTE R MPS range, thus ensuring complete flexibility aimed at satisfying all power and power supply requirements. Riello UPS provides the same flexibility as the Master HP for the battery bus, so that the MHU units can operate with both shared or separate batteries.The 800 kVA MSB is supplied with a comprehensive cabinet including by-pass line input switch (SWBY ), system output switch (SWOUT ) and manual by-pass (SWMB ).
The 1200 kVA model is supplied as standard without any switches but can be equipped with the same, suitably proportioned, switches provided for the 800kVA model (SWBY , SWOUT , SWMB ) The more powerful models are supplied with no switches; the bulky sizes of disconnection devices at these power levels are such as to favour tailor-made engineering solutions as an additional part of the system attestation and distribution cabinets where the centralised by-pass and MHU modules are fitted.

The ideal solution for installations with UPS in parallel greater than 1 MVA
Medium-high power systems are often comprised of N UPS of small-medium power ratings arranged in parallel. It is clear that the larger the size of the individual UPS modules or the number of units configured in parallel, the more complex and extensive the system wiring shall be. Particular attention should be paid to the length of the power lines for the individual UPS bypasses, so that they are equidistant from the common points. Even minimal variations in the line impedances of the individual by-passes can cause current equipartition problems between the UPS and associated overcurrent in the cables whenever they supply from the by-pass. This can lead to the inappropriate cut-in of protection devices and an generate heat, with the end result of minimising power continuity and increasing power consumption for cooling the system. The Riello UPS centralised by-pass (MSB ) is the ideal solution for eliminating all critical issues connected with power distribution over by-pass lines.

In the event that one of the two power sources does not return to the accepted tolerance values, the MASTER SWITCH will transfer the other loads over to the second power source (this happens instantly if the two sources are in phase).


Model Nominal Current (A) Nominal Voltage Dimensions (WxDxH) (mm)
MSB 800 800 380 – 400 – 415 Vac three-phase + N 1000 x 850 x 1900
MSB 1200 1200 380 – 400 – 415 Vac three-phase + N 1400 x 1000 x 1900
MSB 2000 2000 380 – 400 – 415 Vac three-phase + N  2600 x 1000 x 1900
MSB 3000 3000 380 – 400 – 415 Vac three-phase + N 4400 x 1000 x 1900


Nominal power (kVA) See series table
Nominal voltage 380 – 400 – 415 Vac three-phase + N
Input voltage tolerance ± 15% (selectable from ± 10% to ± 25% from front panel)
Frequency 50/60 Hz
Frequency tolerance ± 2% (selectable from ± 1% to ± 6% from front panel)
Standard equipment provided Back Feed protection
Permitted overload* 110% for 60 min; 125% for 10 min; 150% for 1 min
* under certain conditions

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