-Basic Circuits -Power Distribution -Fusing/Protection

Closed Circuit

Open Circuit

Switch

Short Circuit

Normally Open Circuit = open when non-energized and closed when energized Normally Closed Circuit = closed when non-energized and open when energized Normalcy = no electric/ non-energized

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100,000’s volts 100,000,s volts Reduces to thousands 240 volts 12,000 volts harder hall

Transformers -changes voltage P=primary S=secondary Example: 240volt (P) to 24volt (S) 10 to 1 ratio

Power lines Transformer Service wires Service entrance panel Breakers Disconnect box Receptacle

AWG (American Wire Gauge) Amps

Walter de Maria’s The Lightening Field

Richard BoxLight Fields

Series Curcuit Rt = R1 + R2 + R3

Parallel Circuit RT= 1 OR if resisters are same, divide the ohms of one leg by the # 1/R1 +1/R2 + 1/R3 of resister RT = ohms/3

Series Parallel Circuit

Phases Single Phase Three Phase (sine wave)

Delta (3 wire system) Wye ( 4 wire system )

Lets wire: from service panel - 120v receptacle 240v receptacle

Lets wire: From 208 three phase panel - 120v receptacle 208v receptacle

End of 3

Designing for Heat

Volume of ChamberKW RequiredKW increased per C FT 1 c ft3 2 c ft c ft c ft c ft c ft c ft c ft Electric Kiln Construction for the Potter, Robert Fournier Table # 6 Power/volume Relationship Find - Watts per cubic ft ? - Watts per cubic inch

2’ x2’ x 2’ Hot-Face 8 c ft = total watts Watts / cubic ft= Watts / cubic inch = Watts/ square ft= Watts/square inch=

As a general rule: 1 watt / cubic inch (Assuming it’s insulated well) -Cubic inch = -Watts needed= I,D 24” 20”

240 v Amps= -Let include some margin of error, Amps -Size wire needed from panel AWG -Size breaker needed Electrical panel= I,D 24” 20”

AWG (American Wire Gauge) Amps

Ohms Law= Network Resistance= ohms Lets look at Kenthal A-1 Tables Lets use 14 gauge The value given is.2124 ohms/foot I,D 24” 20”

The value given is.2124 ohms/foot We need ohms Each foot has.2124 Ohms needed = Feet of wire.2124 I,D 24” 20”

25 feet of A-1 wire around a 3/8 mandrel would be about 10” long If we connect to 240volts This gives us 40 amps or 9600 watts. This element may heat for a matter of seconds before it burns up. Wait a Minute!!!!! I,D 24” 20”

Why? A-1 Data Table: Find - sq in / ft 14 gauge wire Sq. inches per foot x feet of wire = total sq inches Surface Loading table : Total watts Total sq in = watts/ sq in

We need to use more wire to increase the surface area, but we need to keep our 5.33 ohm Network Resistance Lets go back to Series Parallel Circuits : RT= 1 OR if resisters are same, divide ohms of one leg by the # of 1/R1 +1/R2 resisters RT = ohms/3

Calculate the surface load with our 5.33 N.R. : Lets say: Ohms needed = Feet of wire.2124 Sq. inches per foot x feet of wire = total sq inches x = Total watts Total sq in = watts/ sq in Look to Chart Total Sq inches x 4 Elements = sq inches x 4 = 3.

Total # of elements= 1 st, lets look at how many elements we can fit into the walls and floor.

Lets try (10) ohm elements. Perhaps the following Series-Parallel circuit will work: 5 elements in parallel: 5.33 x 5 = ohms Because we have 2 elements in series : ohms / 2 = ohms Network Resistance=

Calculate the surface load with our 5.33 N.R. : Ohms needed = Feet of wire.2124 Sq. inches per foot x feet of wire = total sq inches x = Total watts Total sq in = watts/ sq in Look to Chart Total Sq inches x 10 Elements = sq inches x 10 = 3. 4.

Coiled 1 ohm = 2” = Stretched length = Feet of wire used Feet of wire = Ohms needed x # of elements.2124 Money spent on wire Cost of spool Feet in spool = cost/ft x total feet used= $

g Kenthal A-1

Control loops

Super-Super-Duper Basic Kiln 120 volts Extension Cord 16 ohm Heating Element Current? Power?

Super-Duper Basic Kiln 240 volts Extension Cord 20 ohm Heating Element Current? Power?

Lets start to control rate of temp. Infinite control switch Bimetal switch Good for switching on and off up to 15 amps

Lets add a kiln sitter Kiln sitter good for up to 50 amps

If we go over 50 amps or would like to use a computer controller Lets add a mechanical contactor ( Relay )

Simplified 3 zones 240v ac

Lets wire our Bartlett controller: 240v 1 zone