Printer in-rush current

[joolsmy]

I recently tested 10 laser printers, all the same model of a well-known brand. I always do a load test and two of the 10 exceeded the wattage shown on the specification plate as they started up.

I didn't fail them as I could see no sign of any problem such as overheating and they were both in use with no reported functional problems. I contacted the importers but they weren't very helpful saying that they didn't support PAT queries.

I'm wondering if these odd readings are indicative of a fault and why just two of the batch should differ from the other eight. Any ideas?

 

[telectrix]

could be related to which part of the supply sine wave is relevant to the point when they kick in. try a few times, see if readings vary.

 

[Pete999]

What do these printer run at after the initial start up procedure? What is the size of the fuse in the plug?

 

[joolsmy]

could be related to which part of the supply sine wave is relevant to the point when they kick in. try a few times, see if readings vary.

I'm no longer on the site so I can't retest at the moment. I did retry one of them two or three times with a pause between, the results were consistent.

 

[joolsmy]

What do these printer run at after the initial start up procedure? What is the size of the fuse in the plug?

5 amp fuse, they drew about 15w after settling down. The plate specified 400w, the two odd ones measured around 900w during start-up whereas the others between 300-400w.

 

[westward10]

When you turn a printer on there is generally inrush current when the heater momentarily kicks in it will then fall into standby or sleep mode. In standby you are looking at 20 to 50w but when the printer is in use it can be 10× this.

 

[joolsmy]

When you turn a printer on there is generally inrush current when the heater momentarily kicks in it will then fall into standby or sleep mode. In standby you are looking at 20 to 50w but when the printer is in use it can be 10× this.

Ok, 900w seemed a bit high to me, especially as only two of them were that high. I've not seen anything on the news about the office burning down though

 

[westward10]

The start up current of a laser printer can be 7 to 10× its running current, this is not uncommon.

 

[joolsmy]

The start up current of a laser printer can be 7 to 10× its running current, this is not uncommon.

Ok, I'll stop worrying then Thanks!