If you’re working with more complex AC or systems, like HVAC controls systems or variable-frequency drives (VFDs), look for a multimeter that provides True RMS, which stands for root mean square.

My DMM is Twintex TM287 (3 5/6 digit True RMS multimeter, 6000 counts with Analog bar), which uses FS9922-DMM4 IC from Fortune Semiconductor Corp., This IC is also used in the DMM UNI-T UT61D. The DMM ...