I have a number of big silicon controlled rectifiers (SCR’s) of the “hockey puck” type.
“Continue reading” for more details and photos.
The ratings of this one (Semikron SKT 1200/12E) are 1200 V at 1200 A. For a 10 ms pulse it can take up to 30,000 A. They need a large amount of compression (22 – 25 kN, about 2.5 tonne) to firmly press the precious metal contact layer onto the silicon to get the best contact.
Above is my SCR clamped with two heavy copper busbars with insulated bolts and is shown short circuiting a car battery at 210 A. I have to use the quick release locking pliers as there is no switch here and once the SCR goes on it stays on.
Here are the autopsy results from one of 4 blown big silicon controlled rectifiers (SCR’s).
Here are pictures of my SCR autopsy. The ceramic is ungrindable and unhacksawable (are these words?), so it came down to gentle caresses with a ball pein hammer and cold chisel. in the last picture I am holding the silicon disc with bonded metal on either side.
Here are SCR’s used in Can Crusher 2 configured as diodes to catch voltage reversal.
Above: The stack of 4 SCR’s with high speed gate diodes and voltage dividers.
The circuit diagram of the stack.
As I have 12 hockey puck SCR’s that I found in the dirt in a junk yard (amazingly) this is the biggest acreage of silicon that I have. Unfortunately I can’t find the SCR’s data (3RW 9103-OCG 5660) but I have tested the forward breakdown at 1800 V. I was hoping they could handle 1000 A with perhaps 30,000 A peak for a 50 Hz half cycle and probably more with a briefer cycle.
Well my SCR stack finally blew when going for 15 kA 3 KV. Still it was successful at 12.5 kA 2.5 kV. This is still a very significant current to go through a single semiconductor. My gate diodes rated at 2 kv were OK.
This is the 1.5 kJ capacitor bank which uses an SCR to switch the power from 4 electrolytic capacitors.
Related pages
Can crusher 2Try something else
External links
Silicon controlled rectifiers – Wikipedia
Photo Date: 2005