How do I test a SCR for Peak Forward Blocking Voltage on my curve tracer?
Peak Forward Blocking Voltage - VDRM
What It Is:
With no gate signal applied, peak forward blocking voltage is the maximum voltage that can be applied to the anode without causing theSCR to enter the unblocked (On) state.
On the curve tracer, the Collector Supply drives the anode and the gate is held open.
What The Display Shows:
The display shows anode voltage on the horizontal axis, and the resulting anode current on the vertical axis. The specification is met when the specified maximum anode voltage can be applied without causing anode current in excess of the specified maximum.
How To Do It:
1. Set controls:
A: Max Peak Volts to the lowest setting above the specified VDRM
B: Max Peak Power Watts to the lowest setting that satisfies (IDRM x VDRM)
C: Horizontal Volts/Div to display VDRM between the 5th and 10th horizontal divisions
D: Vertical Current/Div to display IDRM between the 5th and 10th vertical divisions
E: Collector Supply Polarity to +DC
F: Configuration to (Base/Open, Emitter/Common)
G: Variable Collector Supply to minimum % (full ccw)
H: DotCursor ON
2. Apply power to the SCR:
A: Position the Left/Right switch as appropriate
B: Slowly increase the Variable Collector Supply % until the specified IDRM is attained
3. Compare to data sheet specifications:
Check that at the specified IDRM, VDRM is greater than or equal to the specified minimum
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