Sine Waves and Efficiency of different UPSs


#41

Dear Asad

Please delete it.


#42

Signode if i switch off wapda manually even my pc doesnt restart on homage but when loadshedding occurs means power is shutdown from grid the pc restart...in order to check the pc restarting or not you have to switch on pc on ups just close to loadshedding time and see whether it restarts or not.


#43

[quote=“Pathfinder, post:42, topic:17125”]

Signode if i switch off wapda manually even my pc doesnt restart on homage but when loadshedding occurs means power is shutdown from grid the pc restart…in order to check the pc restarting or not you have to switch on pc on ups just close to loadshedding time and see whether it restarts or not.

[/quote]

Do you know why this strange thing happens with Homage UPS that when you switch off input yourself, desktop PC does not restart and it restarts when power is failed due to load shedding?

Reason (Lets create a scenario): When you switch off input of UPS yourself, power goes from 220 V to suppose 150 V in less than 20 ms and then Homage takes action and starts supplying back up. Therefore desktop computer keeps working normally because PSU can work with voltage as low as 150 V. But when load shedding happens, voltage drops to 150 V taking longer time say 40 ms because electricity is still flowing in wires from grid station to home due to long distance. Homage also has longer switch over time and it switches over to batteries when voltage falls to approximately 90-170 V (it depends upon narrow and wide settings). Since Homage UPS is very sensitive to input current, when power is failed due to courtesy of government, it considers that current is still flowing through its input and when voltage of input falls below 150 V or something like that, it finally switches the output over to batteries. And since less than 150 V is unacceptable for PSU in our scenario, computer restarts. Mostly, a PSU is designed to accept voltage down to 150-160 V (exceptions are there where some PSUs can work with even 100 V). Also PSU has circuitry with certain threshold to deal with sudden electricity fluctuations.


#44

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