These Schematics have been brought over from the "Theory Area" for your convenience.

------Part 1: Boost, Buck and Choke Setups------



Boost Connections

Related Text From Original Post


Topic: Boost Transformer Schematic
Scott35
Moderator
posted 06-18-2001 08:14 PM



Have a few more schematics for everyone to check out!!!

This one is the Infamous "Booster" Transformer.
Connecting a typical Isolated Transformer as shown in the schematics, gives us an Autotransformer - from
which the output voltage can either be raised [as in this schematic], lowered [in following schematics as "Buck"
transformer], or lowered with a "Choking Effect" on the current [in another following schematic as "Choke"
transformer].
Both schematics on each page are equal in function and in connections. I drew both types of schematics, one
to demonstrate the most familiar "Pictorial" drawings - the other is a one-line type schematic.
The one-line drawing should make connections arrangements more easier to follow, which is the reason I
included both drawing types on all the transformer schematics.



Scott SET



Buck Connections

Related Text From Original Post


Topic: Buck Transformer Schematic
Scott35
Moderator
posted 06-18-2001 08:24 PM



Here's another Isolated Transformer, connected as an Autotransformer - in this case, the connections are
Series Subtractive - making it a voltage "Bucking" transformer.
The schematic "Boost Transformer" is very similar, except the connections are made in Series Additive format.
BTW: The "Buck" transformer is a mirrored image of the "Boost", the inputs and outputs are reversed.

FYI: The "PHI" symbol on each schematic represents positions of phase polarity [direction of magnetic flow in
core as to direction of currents in windings]. That's the key issue of how and why these Autotransformers
[connected as Autotransformers] can do the Buck / Boost thingee [technically speaking ]

Scott SET



Choke Connections

Related Text From Original Post


Topic: Choke Transformer Schematic
Scott35
Moderator
posted 06-18-2001 08:38 PM



This connection is similar to the "Boost" transformer, except the relative polarity is Series Subtractive, plus the
connection creates a "Choking Effect" on the current that flows through the secondary coil - hence the name
"Choke Transformer".
This lowers the voltage, plus limits the current.
The current limiting action is similar to how a Ballast functions [Typical Magnetic Reactor, HX, CWA Ballasts
used for HID and Fluorescent lamps].
Maximum output current is based on the secondary winding's ability to create current, so the short circuit
current would be what ever the secondary coul can produce [same as the reactor type Ballast].
Total KVA that can be drawn through the secondary is figured same as any other Buck/Boost transformer - %
of Pri/Sec voltage
Example: 120 x 12 VAC - 1 KVA = 1000% of 1 KVA , or 10 KVA max.
Another example: 240 x 12 VAC - 1 KVA = 500% of 1 KVA, or 5 KVA max.

Hope everyone likes these schematics!!



Scott SET

[This message has been edited by Webmaster (edited 06-18-2001).]

------Part 2: Realtive Polarity Tests------



Related Text From Original Post


Topic: Polarity Test 1
Scott35
Moderator
posted 07-02-2001 03:25 AM

This Schematic shows how to find the relative polarities of Secondary Windings on a 1 phase Split-Coil Secondary
Transformer.

For this test, connect a "Test Jumper" between the Secondary Windings so they are connected in Series.
Using a common DVM [Digital Voltage Meter], measure voltage output, as shown and represented by the "E" in the
circle.



Scott SET - posted 07/02/01



Related Text From Original Post


Topic: Polarity Test 2
Scott35
Moderator
posted 07-02-2001 03:19 AM

This Schematic shows how to find relative polarities of Primary and Secondary Windings on a 1 phase 2 wire
Transformer.

The "Test Jumper" shown [connecting the Primary and Secondary Windings at one end], is used only for this test.
Using a common DVM [Digital Voltage Meter], check the voltage between Primary and Secondary - as shown and
represented by the "E" in the circle.



Scott SET - posted 07/02/01



Related Text From Original Post


Topic: Polarity Test 3
Scott35
Moderator
posted 07-02-2001 03:12 AM

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.

Scott SET - posted 07/02/01


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