MASTER HE
SPTMHEE3T16FREN
6
Centralized By-pass: Master Static Bypass (MSB)
The configuration with centralized By-pass comprises up to UPS modules (MHE NBP type) having not embedded static
switch connected in parallel and a separated By-pass section. The By-pass unit is equipped with a static switch which
automatically switches the power supplied to the load by the whole system directly to the mains power supply and vice
versa. Switching is needed during system maintenance operations, or when the whole system is unable to support the
load due to overloads or output short circuits over the current limits.
This configuration assumes the selection of n UPS modules having the same power rating.
The following site prescriptions should be taken into account for the site planning:
•
Distance between UPS module and central by-pass shall not exceed 40 meters
•
Communication bus cable between units shall not exceed 50 meters
•
Total communication ring (UPS units and by-pass) shall not exceed 150 meters
•
Battery can be arranged as common or separate (same as distributed parallel system)
•
Maintenance bypass is part of the system either embedded in Riello UPS solution (Fig. 1) or supplied by the
customer together with all Input/Output/distribution switches (Fig. 2)
This manually control switch will enable the load feeding directly from the mains insulating the UPS whenever
there is an intervention on its critical parts.
According with site arrangement and UPS modules pairing layout, it will be possible to arrange for MSB having switches
inside (Fig 1) or MSB without any breaker, leaving the coupling arrangement to the customer which shall ensure handy
and safe operations during maintenance. (Fig 2)
These two different layouts modify the system current reading but it won’t affect the system operation.
Below we resume the two different scenarios according with system operations either on Inverter or bypass mode:
Display MHE NBP
Display MHE MSB
Riello UPS will provide the system as for Fig. 1
System on
inverter
Unit current in: kW, kVA, peak, rms and %
refers to single unit capacity
System current in: kW, kVA, peak, rms, and %
refers to MSB capacity
System on static
bypass
No info
System current in: kW, kVA, peak, rms and %
referred to MSB capacity with inverters locked
(fault) or % referred to unit modules with
inverters ready to supply load.
Riello UPS will provide the system as for Fig. 2
System on
inverter
Unit current in: kW, kVA, peak, rms and %
refers to single unit capacity
System current in % referred to unit module
(master one will pass the data) and not MSB
capacity
System on static
bypass
No info
System current in: kW, kVA, peak, rms and %
referred to MSB capacity with inverters locked
(fault) or % referred to unit modules with
inverters ready to supply load.
