Pilot Communications EGO700, Installation & Operation Manual, Page: 16 / 30

5.8 Unbalance
In an ideal three-phase power supply system, the ABC three-phase voltage and
current amplitude are equal, and the phase difference is 120°, and it is in a balanced
state at this time. When the actual system deviates from the above situation, the
problem of imbalance and the corresponding reduction of power utilization efficiency
will occur.
EGO700 can measure the positive sequence, negative sequence and zero
sequence amplitude of voltage and current, and calculate and analyze the voltage and
current imbalance.
The voltage and current unbalance calculation formula is as follows:
Voltage unbalance=(Negative sequence component of voltage/Positive sequence
component of voltage)x100%
Current unbalance = (current negative sequence component/current positive sequence
component) x 100%
The zero sequence current
0
I
calculation formula is as follows:
3
) cos cos cos ( ) sin sin sin (
0
2 2
ic Ic ib Ib ia Ia ic Ic ib Ib ia Ia
I
          

In the formula:
Ia stands for A phase current
Ib stands for B phase current
Ic stands for C phase current
ia represents the phase angle of phase A current
ib represents the phase angle of phase B current
ic represents the phase angle of phase C current
5.9 Fixed value alarm
The fixed value alarm parameters of the EGO700 device can be set by the host
computer software through communication. When an alarm event occurs, the alarm
type can be read through communication. There are 22 groups of monitored alarm
objects, and each group of parameters includes the following:
(1) Action mode: on/off.
When this monitoring is enabled, the alarm object will monitor and alarm.
(2) Action value: the action value and return value of the over-limit trigger.
For the upper limit, when the measured value is greater than the action value,
takes action, and when the measured value is less than the action value, returns;
For the lower limit, when the measured value is less than the action value, takes
action,, and when it is greater than the action value, returns;
(3) Action delay time: the time to delay action after the limit is exceeded.
The setting range of the action delay time is 0~120s.
Monitoring and alarm objects include: A-phase voltage upper limit, B-phase
voltage upper limit, C-phase voltage upper limit, A-phase voltage lower limit,