ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals

ECN Shout Chat
Top Posters(30 Days)
Admin 19
Recent Posts
Anyone hiring inspectors?
by HotLine1. 03/27/17 08:03 AM
Old decora style outlets
by Admin. 03/25/17 11:40 AM
ESA Arc flash course
by TheShockDoctors. 03/24/17 10:15 AM
fuse rejectors
by HotLine1. 03/24/17 07:53 AM
Another Forum Update
by Admin. 03/22/17 03:04 PM
New in the Gallery:
SE cable question
Popular Topics(Views)
231,583 Are you busy
166,394 Re: Forum
160,691 Need opinion
Who's Online Now
1 registered members (HotLine1), 76 guests, and 15 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate This Thread
#129200 - 10/20/04 03:53 PM power factor at meter  
james S  Offline
Member
Joined: May 2003
Posts: 107
West England
From my understanding if you had an installation with large inductive loads, well the reactive part of the loads is not registered on the incoming meter and so the wattless current is free of charge, and so the supply company likes to fine you for having poor power factors.
My question is why does the meter not see the wattless current, the meter does not know the current is going towards inductive reactance.the only vairable to work off at the metre is the current.
any help would be much appreciated


Tools for Electricians:

#129201 - 10/20/04 04:34 PM Re: power factor at meter  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,211
SI,New Zealand
James,
The reason the Watt-Hour meter does not register Reactive power, is because the reactive power does no real work but it still has to be allowed for in cable calcs. Only True Power (V x I) does work, ie: creates heat or light, this is what the watt-hour meter is designed to indicate


Let's face it, these days if you're not young, you're old - Red Green grin

#129202 - 10/21/04 09:48 AM Re: power factor at meter  
james S  Offline
Member
Joined: May 2003
Posts: 107
West England
Although the reactive power does no real work there is still its current flowing in the supply cables, now if the metre uses current to work out a watt rating the metre is going to read the wattless current.
i suppose the question is how does the watt meter measure watts?


#129203 - 10/21/04 02:22 PM Re: power factor at meter  
cpal  Offline
Member
Joined: May 2004
Posts: 162
Cohasset MA
Reactive power is the product of a negitive multiplied by a positive factor. If you consider a sine wave with the voltage and current in phase the product of the two will yield a positive value + time a +, for one half cycle then a - times a - the next half cycle. this will always equals a positive product.

When reactive loads are installed the current and voltage are not always in phase and at times the instantanious valuesare of opposite polarity, this will yield a positive and negitive factor of which the product will have a negitive value( + times - equals a - product).

Negitive watts does not record on a watt meter. thus phantom power

[This message has been edited by cpal (edited 10-21-2004).]



Member Spotlight
HappyElectrician
HappyElectrician
Penn USA
Posts: 31
Joined: December 2011
Show All Member Profiles 
Featured:

2017 NEC and Related
2017 NEC
Now Available!

Shout Box
Powered by UBB.threads™ PHP Forum Software 7.6.0
Page Time: 0.016s Queries: 14 (0.003s) Memory: 0.7585 MB (Peak: 0.8903 MB) Zlib enabled. Server Time: 2017-03-27 20:33:12 UTC