Geekzone: technology news, blogs, forums
Welcome Guest.
You haven't logged in yet. If you don't have an account you can register now.

565 posts

Ultimate Geek

# 183704 27-Oct-2015 12:36
Send private message

I have a Japanese device which lists a power rating of 100V 500VA.

The device is plugged into a to a 240v to 100v 1000VA step down transformer (which comes with the device from the manufacturer).

A power meter measures the device power consumption at <200W (~130W) at the wall (inc transofrmer).

I'm looking to protect the device with a UPS for 3-5min and want to confirm size of the UPS I should be looking at.

Should I go by the measured consumption of 200W, the device rating of 500VA or transformer rating of 1000VA?

Create new topic
195 posts

Master Geek


  # 1415070 27-Oct-2015 20:35
Send private message

What kind of device is it? If it's motorised, you may need a UPS capable of delivering much more current than a simple P=EI calculation would suggest.

Does your power meter tell you the power factor of your device?

22739 posts

Uber Geek


  # 1415095 27-Oct-2015 21:30
Send private message

UPS's usually are a pretty bad inverter in them, and that makes transformers unhappy. The 24V AC one for my sprinkler controller cooked itself on the last power outage when it was running on the UPS. Not sure how the stepdown would get on with that.

What on earth needs a stepdown transfromer and a UPS tho?



984 posts

Ultimate Geek

  # 1415101 27-Oct-2015 21:35
Send private message

If you have measured the total power consumption at ~200 W at source then that includes all conversions in the transformer.

Does the consuming device have the ability to operate in any other modes that draw more power ? What is it?
For example , was it a thing that had already heated up? If the load device goes into a mode and draws 500VA while on UPS, the backup time will drop to 40% of the time you think you're going to get at 200W(~VA).

The transformer rating is irrelevant to your UPS requirement as it only determines the maximum transformer load. Load is maximum 500 W(~VA), typical 200 W.

Create new topic

Twitter and LinkedIn »

Follow us to receive Twitter updates when new discussions are posted in our forums:

Follow us to receive Twitter updates when news items and blogs are posted in our frontpage:

Follow us to receive Twitter updates when tech item prices are listed in our price comparison site:

News »

Intel introduces cryogenic control chip to enable quantum computers
Posted 10-Dec-2019 21:32

Vodafone 5G service live in four cities
Posted 10-Dec-2019 08:30

Samsung Galaxy Fold now available in New Zealand
Posted 6-Dec-2019 00:01

NZ company oDocs awarded US$ 100,000 Dubai World Expo grant
Posted 5-Dec-2019 16:00

New Zealand Rugby Selects AWS-Powered Analytics for Deeper Game Insights
Posted 5-Dec-2019 11:33

IMAGR and Farro bring checkout-less supermarket shopping to New Zealand
Posted 5-Dec-2019 09:07

Wellington Airport becomes first 5G connected airport in the country
Posted 3-Dec-2019 08:42

MetService secures Al Jazeera as a new weather client
Posted 28-Nov-2019 09:40

NZ a top 10 connected nation with stage one of ultra-fast broadband roll-out completed
Posted 24-Nov-2019 14:15

Microsoft Translator understands te reo Māori
Posted 22-Nov-2019 08:46

Chorus to launch Hyperfibre service
Posted 18-Nov-2019 15:00

Microsoft launches first Experience Center worldwide for Asia Pacific in Singapore
Posted 13-Nov-2019 13:08

Disney+ comes to LG Smart TVs
Posted 13-Nov-2019 12:55

Spark launches new wireless broadband "Unplan Metro"
Posted 11-Nov-2019 08:19

Malwarebytes overhauls flagship product with new UI, faster engine and lighter footprint
Posted 6-Nov-2019 11:48

Geekzone Live »

Try automatic live updates from Geekzone directly in your browser, without refreshing the page, with Geekzone Live now.

Support Geekzone »

Our community of supporters help make Geekzone possible. Click the button below to join them.

Support Geezone on PressPatron

Are you subscribed to our RSS feed? You can download the latest headlines and summaries from our stories directly to your computer or smartphone by using a feed reader.

Alternatively, you can receive a daily email with Geekzone updates.