Hioki 3196 - Page 24

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Summary of analysis3.
Worse power supply quality occurs frequently at night (9 p.m. to 9 a.m.).1)
Worse power quality phenomena starts when the voltage dips.2)
Voltage swell occurs when switching from the commercial power to the UPS due to the
voltage dip.
3)
The voltage dip occurs when the commercial power recovers and the power supply is
switched from the UPS to the commercial supply.
4)
Countermeasures4.
Primary solution1)
Alternative solution2)
Frequent switching to the UPS because of a voltage dip is not favorable. It appears
that overload current flows to the equipment due to voltage dips and swells. To
solve this problem without fail, the power supply should be stabilized to prevent the
occurrence of a voltage dip.
The UPS is used as a "stand-by power system (SPS)." By changing it to an albeit
more costly "on-line UPS system", the dips and swells can be reduced during UPS
switching.
Circuit example of
Stand-By Power
System
Circuit example of
On-Line UPS System
Circuit example of
Line-Interactive System
[#] Alternate connection to AC input is allowed.
[##] Blocking diode, cyclister or switch
Switch
AC
output
Charger
(option)
Rectifier Inverter
[##]
AC input [#]
AC input [#]
AC input [#]
Normal operation
Charged energy
operation
Bypass operation
Bipass
DC link
Rechargeable
batteries
Power
interface
[##]
Normal operation
Charged energy
operation
AC outputAC input
Rechargeable
batteries
Charger
UPS
AC
output
Bypass
Inverter
AC input [#]
AC input [#]
[#] Alternate connection to AC input is allowed.
Normal operation
Charged energy
operation
Optional connection