MECO PSI 2016 is a 3-phase Phase Sequence Indicator. Its main job is to check whether the three phases of an AC electrical supply are connected in the correct sequence, and to detect reverse phase or missing / open phase conditions.
What is “phase sequence”?
In a three-phase system, the phases are commonly identified as:
R → Y → B
or
L1 → L2 → L3
The order in which these phases reach their voltage peaks determines the phase sequence/rotation.
For example:
Correct sequence: R → Y → B → motor rotates in the intended direction.
If two phases are interchanged:
R → B → Y → motor rotation reverses.
This is particularly important for three-phase motors, pumps, compressors, fans and other rotating equipment. An incorrect sequence can make a motor rotate in the wrong direction and potentially cause equipment problems.
The instrument can indicate three basic conditions:
Correct Phase Sequence (CW) → 3 Yellow LEDs + Green LED → Intermittent Beep
Reverse Phase Sequence (CCW) → 3 Yellow LEDs + Red LED → Continuous Beep
Open / Missing Phase → Corresponding Phase LED OFF → Continuous Beep