YOKOGAWA CW120 - Page 150

14-2
IM CW120-E
14.1 Specifications of CW120/121
(3) Instantaneous Value Measurement
Measured parameters Rms voltage (V), rms current (A), active power
(W), frequency (Hz)
Measurement accuracy At power factor = 1 (including clamp-on probes)
Voltage ±(0.3% rdg + 0.2% rng)
Current and active power
±(0.8% rdg + 0.4% rng) with probe 96030, 96031,
or 96033
±(1.2% rdg + 0.8% rng) with probe 96032
Frequency ±(0.1% rdg + 1 dgt)
Calculated parameters Reactive power (Var), power factor
Calculation accuracy (Value calculated from measurement) ± 1 dgt
Power factor effects ±1.0% rng cos φ = ±0.5 (relative to power factor 1)
with probe 96030
±2.0% rng cos φ = ±0.5 (relative to power factor 1)
with probe 96031, 96032, or 96033
Reactive factor effects ±1.0% rng sin φ = ±0.5 (relative to reactive factor 1)
with probe 96030
±2.0% rng sin φ = ±0.5 (relative to reactive factor 1)
with probe 96031, 96032, or 96033
(4) Equations
Rms voltage
Vrms =
T
1
v(t)
2

T
t=0
T
1

v(t)
dt =
T
0
2
Rms current
Arms =
T
1
i(t)
2

T
t=0
T
1

i(t)
dt =
T
0
2
Active power
T
1
v(t) ~ i(t)

T
t=0
T
1

v(t) ~ i(t)dt =
T
0
P =
Single-phase three wires (1ø3W) or three-phase
three wires (3ø3W): ∑P = P1 + P2
Three-phase four wires (3ø4W): ∑P = P1 + P2 +P3
v(i), i(t): Input signals
T: One cycle of input signal