Circuit Breaker Components

• Capacitor

• Resistors

• Diodes

• Switches

Capacitors--Specs

• 10KVDC

• 10uF

• Small Size

• Three sources– Plastic Capacitors Inc (USA)– Hi Volt Corporation (Ireland)– High Energy Corporation (USA)

Capacitors

• Size is a function of Capacitance– Smaller capacitance, smaller volume

Possible to use smaller cap?

• 10uF gives a spike of 12kV for about 200msec

• 1uF gives a spike of 14kV for about 100msec

• Is this acceptable?

• Try simulations with 5uF

Capacitor Comparison

Plastic Caps Hi Volt High Energy

materials Sealed military can,

Solder-seal terminals

Tinplate case,

Ceramic terminals

Enamel finish

Plated steel, epoxy finish

Impregnant Mineral oil Mineral oil Mineral oil

Applications Storage/dischage, high current low repetiton

Arc and spark suppression,

Voltage smoothing

Filters

Cap Comparison (cont)

• Tolerances of ±10%

• Temperature ranges –55C to 85C

• Prices (based on purchase of 100-150 units)– Plastic Caps range from $112 for 1uF to $493

for 10uF– Hi Volt prices at £70 fro 1uF and 4uF

Resistors--specs

• 1kΩ resistance

• 10 Amps

• 10kVDC

• 10A*10kV=100kW!

• 100kW*1sec=27.77kWh

• 27.22kWh/3.6*10^6=7.7*10^-6 Joules

Resistors—what I found

• Most resistors very small or very large• Most resistors rated in KW range are very

large size and impractical for our purposes• High voltage resistors are rated for low

wattage and high energy• Ex.

Kanthal Globar 106AS resistor15kV, 35A, 13W, 1900J

Resistors

• Actual resistance value still undecided

• Actual ratings not entirely clear, i.e. what power ratings and energy ratings will suffice for this application.

• Wait until design is more firm, test resistors in lab

Resistors (cont)

• Manufacturers– Kanthal Globar

• Resistors designed for short pulses• $43-$73 range per resistor (based on small order)• Sizes from 2”-6” in length

– Nicrom Ticino• Power resistors• $55-$75 range• 2”-6” length

– Tepro • Will build to our specs, 400mm in length

What we have

• Capacitors– No problem

• Switches– Will use vacuum switches for now– Looking into GTO

• Diodes– Again, no problem

Diodes

• Need 10A, 10kV Vrrm• Found 10-20A, 1000-1600Vrrm• Can cascade in series• International Rectifier

– Two types• Plastic casing, $1.26-$1.68ea

• Metal casing $3.72-$3.84ea

• Both about 1.25” in length

• Neither immersable in transformer oil

Switches

• Possible options– Vacuum switches

• Durable, long lasting• Require continuous signal while closed• 3.25” long, 0.65” wide

– GTO switches• Turn on signal, turn off signal, but no continuous

current

What’s next?

• Build a low-voltage prototype

• What we have– IGBT switches– Logic switch controller

• What we need– Low voltage capacitor, resistors, diodes