Tektronix TekScope THS 710, User Manual

Page: 55 / 197

Application Examples
2–30
THS 710 & THS 720 User Manual
Triggering at a Specific Motor RPM
You need to measure the start-up current of a 3600-RPM motor at
several specific speeds. A tachometer, attached to the motor,
outputs a low-voltage square wave with 100 pulses per revolution.
Set up the TekScope instrument to trigger at 1200 RPM so you can
measure the current at that speed.
Ch 1 Ch 2
Tachometer output frequency
1200 rev min 100 pulses rev
60 s min
2 kHz
Tachometer pulse width
period
2
1
2 kHz
2
250 s
Electric motor with
attached tachometer
Tachometer signal (Ch 1)
Motor current (Ch 2)
@: 12.8 A
100 mV/A