3-Phase RMS Meter

Root-mean-square meter for a three-phase scalar signal triple (A, B, C). The Measurement selector picks line-to-line (LL, default) or per-phase line-to-neutral (LN). LN computes out = sqrt(mean((a² + b² + c²) / 3)); LL computes the RMS of the phase differences out = sqrt(mean(((a−b)² + (b−c)² + (c−a)²) / 3)). Both are taken over a sliding 1/frequency window. For a BALANCED three-phase sinusoid LN settles at the per-phase RMS amplitude (A_pk / √2) and LL at √3 times that — e.g. wire the three phase voltages of a 480 V (LL) / 277 V (LN) source in and LN reads 277 while LL reads 480. For UNBALANCED or harmonic-laden inputs the window smooths the per-step variation and the result is the true RMS of the selected quantity. An optional per-unit mode divides the output by a user-supplied base.

Category: Continuous

Ports

Name	Direction	Value type	Notes
in_a	input	double
in_b	input	double
in_c	input	double
out	output	double

Parameters

Name	Label	Type	Default	Units	Description
frequency	f	double	60	—	Fundamental frequency used to size the averaging window (window = 1 / frequency). For BALANCED three-phase sinusoidal inputs the window is technically unnecessary — (a² + b² + c²) / 3 is already constant in time — but a finite window is needed to suppress per-step variation on unbalanced or distorted inputs. Set to your AC system's nominal frequency (60 in North America, 50 in Europe).
measurement	Measurement	enum (Per-phase (LN) / Line-to-line (LL))	line	—	What the meter reports from the three phase (line-to-neutral) inputs a, b, c. `Line-to-line (LL)` is the RMS of the differences: sqrt(mean(((a−b)² + (b−c)² + (c−a)²) / 3)) — the true LL magnitude, correct even when the phases are unbalanced, and equal to √3·LN for a balanced set. `Per-phase (LN)` is the per-phase RMS sqrt(mean((a² + b² + c²) / 3)). Pick LL for a 480 V (LL) reading, LN for a 277 V (LN) reading.
output_pu	Output in pu	enum (Off / On)	0	—	When On, the meter divides its RMS output by a user-supplied base so the result is reported in per-unit. Off leaves the output in the input's absolute units (V or A). A base of 0 (or negative) falls back to absolute units, so pu mode can never produce a divide-by-zero.
base	Base	double	1	V (V, kV, A, kA)	Per-unit base magnitude the RMS output is divided by. Generic — pick the unit that matches the measured signal (V / kV for a voltage, A / kA for a current). Only used when Output in pu is On.