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5.2 Nipron's NSP Power supply
5.2.1 Operating pronciple and its feature

Nonstop power supply has two gates (two inputs) of AC and DC, and two engines ( two converters) that are entirely insulated each other. This is called 2G (two gates)-2E (two engines) system which handles two inputs (AC and DC) at a time with one high frequency transformer.
We provide, as products, one type which works only for the purpose of backup at blackout, and another type with AC and DC input that can be started up regardless of input voltage, AC or DC.

Figure 5.2 Nonstop power supply principle diagram
Figure 5.2 Nonstop power supply principle diagram

Usually electric power is supplied from AC side. In the case that AC voltage falls or blackout occurs, DC side provides electric energy to take over AC operation. Therefore, secondary output is guaranteed to continuously keep on working without any damage to computer system.

Comparing the above to water flow shown in the figure below, water always flows out of either tank, regular tank (AC input) or emergency tank (DC input), which has higher pressure to keep the water level constant.

Figure 5.3 Comparing to water flow
Figure 5.3 Comparing to water flow

<< Comparison with existing system (serial converter system) >>
Major system of UPS with DC output has been serial converter system. Its problem is that charger and converter are connected in series resulting in poor efficiency and large size. With one transformer which connects AC input and DC input by parallel converter system, high efficiency and compact size is materialized.

Table 5.1 Comparison with existing system

Comparison items

Existing UPS system (Series converter system)
Existing UPS system (Series converter system)
Nipron Nonstop system (parallel converter system)
Nipron Nonstop system (parallel converter system)

Efficiency is 10% or less resulting in 64% to 72% due to series connection, although efficiency has been improved of late.

Efficiency is significantly high due to parallel
Dimension Price Significantly larger and more expensive than parallel system. Compared with series system, dimension and cost
are improved by approx. 10 to 20% due to
higher efficiency.
EMI noise and Counter-measures

Interference with other equipments

Switching psu (charger) of front end and DC-DC converter (latter part) have its own different switching frequency generating a wider range of noise components. Also, measures against EMI is difficult and need larger noise filter. However, there would be no significant difference only if ingenuity in circuit design is achieved. AC side converter and DC side converter is operated using the same and synchronous switching frequency from sole controller of PWM-voltage regulator. Also, charger is operated by phase control that is within the width of ON pulse of the same switching frequency. Thus, this system makes less EMI noise and brings easier measures to deal with it. This system of one frequency method is especially recommended and suitable for power supply system for tele-communication devices.
Reliability to converter failure As consisting of switching converters that operate individually, when any of the two fails due to accident, entire system comes to shut down. As sole PWM controller handles two converters in parallel synchronously, in case any of them should fail for some reason, the other would take over power
distribution automatically. Thus, the system is safe and has high reliability in comparison with series system.
Power factor Harmonic current interference No difference No difference

<< Differences in NSP series >>

Table 5.2 Differences in NSP series
  Point of defference
Series name   Startup with only DC input connected When power is turned off by remote ON/OFF during DC backup operation.
Battery check terminal (*Note)
PNSP series
cNSP series
NSP2 series

Startup available

Can be used under the envi-ronment where there is no AC input.

When DC input is connected, 5VSB is delivered.

(Except NSP2-250-D2S7)

5VSB is continuously delivered.(Except NSP2-250-D2S7)


VNSP series
NSP2B series

Startup available

Can be used under the environment where there is no AC input.

When DC input is connected, 5VSB is delivered.

5VSB is continuously delivered.(Except NSP2B series)
Not equipped
GNSP series
NSP3 series
eNSP4 series
eNSP3 series
eNSP series
aNSP series

Startup unavailable

Startup is available only when AC input is connected. DC is just for backup when AC is abnormal.

5VSB will not be delivered even when DC input is in connection.

All outputs including 5VSB shut down.

Shutdown operation for external UPS is not required as all outputs are shut down including 5VSB by remote ON signal.

Not available
Startup available
5VSB is continuously delivered.
NSP7-100- X2S2 Startup unavailable All outputs including 5VSB shut down. Optional

* Note: Battery check terminal
When signal "L" is given to battery check terminal.
AC side converter is forcibly turned off to change to DC operation. By this operation, remaining capacity of battery and connection abnormality of connector can be checked.