VAMP Ltd
Power monitoring unit
Technical description
VAMP 260
VM260.EN004
Vamp 24h support phone : +358 (0)20 753 3264
5
2.
Functions
The individual alarm stages of the power monitoring unit
VAMP 260 can independently of each other be enabled or
disabled according to the requirements of the intended
application. See the configuration instructions, Chapter 5 and
7, in the first part of this manual.
2.1.
Principles of the numerical measuring
technique
The power-monitoring unit VAMP 260 is fully designed using
numerical technology. This means that all signal filtering,
measuring and control functions are implemented through
digital processing.
The numerical technique used in the unit is primarily based on
an adapted fast Fourier transformation (FFT), in which the
number of calculations (multiplications and additions) required
to filter out the measuring quantities remains reasonable.
By using synchronized sampling of the measured signal
(voltage or current) and a sample rate according to the 2
n
series, the FFT technique leads to a solution, which can be
realized with just a 16-bit microcontroller, without using a
separate DSP (Digital Signal Processor).
The synchronized sampling means an even number of 2
n
samples per period, e.g. 16 or 32 samples per period. This
means that the frequency must be measured and the number of
samples per period must be controlled accordingly, so that the
number of samples per period remains constant, if the
frequency changes.
2.2.
Measurement functions
2.2.1.
Fundamental frequency measurement
The device calculates the active (P), reactive (Q), apparent
power (S) and energy measures (E+, Eq+, E-, Eq-) from voltage
and current measurements.
