VAMP 257 - Fundamental Frequency Measurement

VAMP 257 Feeder and motor manager
Technical description
VAMP Ltd
82
VAMP 24h support phone : +358 (0)20 753 3264
VM257.EN002
2.4. Measurement functions
2.4.1. Fundamental frequency measurement
All the measurements, except frequency, are based on
fundamental frequency values. They are not RMS values.
The device calculates the active (P), reactive (Q), apparent
power (S) and energy measures (E+, Eq+, E-, Eq-)* from
voltage and current measurements.
Phase currents I
L1
, I
L2
, I
L3
Measuring range 0 - 50 x I
n
I
n
= 1 A or 5 A
Phase voltages U
L1
, U
L2
, U
L3
Measuring range 0 - 175 V ac
Earth fault currents I
0
, I
02
Measuring range 0 - 5 x I
mode
I
n
= 1 A or 5 A
Residual voltage U
0
Measuring range 0 - 175 V ac
Frequency f
Measuring range 16 - 75 Hz
2.4.2. Power calculations
The power calculations in the VAMP feeder terminals are
dependant on the voltage measurement mode, see chapter 4.2.
The formulas used by the feeder terminals for power
calculations are found in this chapter
Phase to neutral voltages measured (Phase mode)
Active power calculation for one phase:
ϕ
cos
111
⋅
⋅
=
LLL
IUP
Reactive power calculation for one phase:
ϕ
sin
111
⋅
⋅
=
LLL
IUQ
where,
U
L1
= Measured L1 phase voltage
I
L1
= Measured L1 current
ϕ = Angle between U
L1
and I
L1