ECN Electrical Forum - Discussion Forums for Electricians, Inspectors and Related Professionals
ECN Shout Chat
Shout Box
Recent Posts
AreMetal Ladders Ever OK For Electrical Work?
by jwes2699. 01/21/18 05:58 PM
VDE 0100 to introduce AFCIs
by sparky. 01/20/18 05:09 PM
MRI LED lights dimmer control replacement - wow!
by Potseal. 01/19/18 08:52 PM
Video: Inventor of the GFCI self-testing shocks
by Bill Addiss. 01/17/18 11:11 PM
New in the Gallery:
Housebilding DIY wiring
SE cable question
Who's Online Now
0 registered members (), 16 guests, and 11 spiders.
Key: Admin, Global Mod, Mod
Previous Thread
Next Thread
Print Thread
Rate Thread
Polarity Test 3 #127421
07/02/01 02:12 AM
07/02/01 02:12 AM
Scott35  Offline
OP
Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
[Linked Image]

This Schematic demonstrates how to find relative polarities of two individual and separate 1 phase 2 wire transformers.

The series connection between the Secondary Windings is a "Test Jumper", which is used only during the test procedures.
Test equipment consists of a common DVM [Digital Voltage Meter] - which is represented by the "E" in the circle.

**NOTE** Both Transformers need to be identical for Pri/Sec voltage, KVA and Z.

Any Comments???

Scott SET - posted 07/02/01


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!
Tools for Electricians:
Re: Polarity Test 3 #127422
07/03/01 02:54 PM
07/03/01 02:54 PM
A
Anonymous
Unregistered

This is a great pair of diagrams!

It shows how when voltages are of the same polarity, they subtract; but of opposite polarity, they add.

Re: Polarity Test 3 #127423
07/07/01 04:02 PM
07/07/01 04:02 PM
Scott35  Offline
OP
Broom Pusher and
Member
Joined: Oct 2000
Posts: 2,708
Anaheim, CA. USA
Dspark,

Thanks for the reply!!! Glad the schematics are of use to the members of this forum.

As you said, the schematic demonstrates how relative polarity can either add voltages ["in phase" connections], or subtract voltages ["out of phase" connections].

It's all according to the direction of current flow on the secondary coil[s] - Vs - the magnetic flow in the core.

These polarity test schematics are really aimed more at the "How-To" or the "FYI" angle of things, rather than at anything that is trade applicable [except that anyone performing "in the field transformer connections" would benifit from this info.].

This particular schematic would be helpful if someone was planning to connect two separate transformers for a common output [Parallel Primary connections, Parallel, Series, or even "Multiwire" Secondary connections].

Transformers need to be exactly the same - even as much as being "Cloned" from the other - in order to function properly.
This meaning that not just the input/output voltage being the same, but the core material, winding density, KVA, %Z, reflected Z and all that jazz. Otherwise one winding will circulate a large level of current.

*** NOTE ***
The NEC does not allow the permanent usage of Paralleled Transformers!!! I can understand the reason[s] why!!!
so much for the disclaimer!

Once again, thank you!!! Glad these schematics are of interest.

P.S. Do you have any drawings, or similar tech. data that you could post here???
If you have any suggested item[s]. let me know. Feel free to contact me directly via E-Mail.
I am adding more mail filters to sift through the massive spam assults, so anyone planning to E-Mail me directly, please include:

Per the ECN forum

at the beginning of the "Subject" heading.
This will place your message in the ECN Members' folder, rather than in the "Inbox" which gets trashed and emptied instantly.
Once I record a member's address, the filter script doesn't need to be used for future messages.

Scott SET


Scott " 35 " Thompson
Just Say NO To Green Eggs And Ham!

Featured:

2017 Master Electrician Exam Preparation Combos
2017 NEC Electrician
Exam Prep Combos:
Master / Journeyman

 

Member Spotlight
JoeKP
JoeKP
Berkley, MA
Posts: 144
Joined: March 2008
Show All Member Profiles 
Top Posters(30 Days)
Admin 20
sparky 16
Potseal 15
Popular Topics(Views)
243,587 Are you busy
180,382 Re: Forum
170,859 Need opinion
Powered by UBB.threads™ PHP Forum Software 7.6.1
(Release build 20180101)
Page Time: 0.017s Queries: 14 (0.004s) Memory: 0.9505 MB (Peak: 1.0751 MB) Zlib enabled. Server Time: 2018-01-22 02:21:26 UTC