Hi,
There is a lot of interest in electronic loads. I am going to share some pictures of an Acme PS2L-1000 load that I was working on.
This load is 60V Max, 110A Max, 1kW Max
This load is about 40 years old, but it shows how the load was constructed. I had the unit apart for cleaning and electrolytic capacitor replacement. The load will work in constant current and / or constant resistance modes.
ManualThe manual can be found here:
http://userequip.com/files/specs/3577/ACME%20PS2L-500,%20PS2L-1000%20Operating%20&%20Troubleshooting%20Guide.pdfThe manual contains partial schematics.
PicturesThe leads are long enough to allow the front panel to be laid down.
This shows the back of the front panel.
Heatsink assemblyThe heatsink assembly can be removed, for maintenance. The transistors are electrically connected to the heatsink. The heatsink doubles as the positive bus bar.
There is a large stud diode and stud SCR. These are for reverse polarity and Over-voltage protection. They will blow the 130A fuse.
Transistor DetailsThere are nine T0-3 transistor on each heatsink:
The transistors are mounted in sockets. Each transistor has 0.4
emitter resistor.
There is no shunt. The current is measured by averaging the voltage across all the emitter resistors.
There are 34 transistors, that is 1000/34 = 29W per transistor.
Control BoardHere is a picture of the control board. It is a single sided board. I will replace the electrolytic capacitors.
Regards,
Jay_Diddy_B