Page 6
Reactive Power Controller
= Key 1 = Key 2 = Key 3
Switching of capacitor stages
Prophi calculates the required reactive power to reach
the set target-cos(phi) from the current from one outer
conductor and the voltage between two outer conduc-
tors. If the cos(phi) deviates from target cos(phi), exter-
nal capacitor stages or transistor outputs are switched
on or off.
In automatic mode the capacitor stages are switched in
or off, when the required reactive power is higher or
equal to the smallest stage power.
If the power of the first capacitor stage is three times as
high as the measured real power, all capacitor stages
are switched off.
Switching outputs
Depending on the variety of Prophi, relay or transistor
outputs serve as switching outputs.
The relay outputs are suitable for controlling contactors
and the transistor outputs can switch thyristor modules,
that switch in zero crossing of voltage.
For relay outputs the time between two connections or
disconnections is set to two seconds. Transistor outputs
have no limitation of the switching period.
Net return
After net return, the set discharge time runs for the
relay outputs. The transistor outputs do not mention the
discharge time.
Funktional description
Measurement
The measurement is suited for 3 phase systems with or
without neutral conductor for frequencies of 50Hz or
60Hz. The electronical measurement system records and
digitalizes the effective values of voltage between L2
and L3 (L-N Option) and the current in L1.
In each second several snap check measurements are
carried out. As the current is only measured in one
outer conductor, and the voltage only between two outer
conductors, the measured values, which are related to
all three outer conductors, are exact for equal loaded
outer conductors only.
The following electrical quantities are calculated:
Current and current harmonics
Voltage and voltage harmonics
Real power, sum
Apparent power,sum
Reactive power, sum
Reactive power for each stage
Reactive current for each stage
Cos(phi),
Net frequency.
The following information can be indicated:
Number of switchings of each stage,
total connection time of each stage and
the inner temperature.
Prophi measures the frequency of the measurement and
supply voltage and shows the average over 10 seconds.
To Next Page
Loading...
Need help?
General
