Technical documentation
Rev. 02
Reactive Factor Controller CX plus
66
12.4 THD-U / THD-I protection
The controller shall protect the active steps by switch-off in case the entire harmonic distortion on the
voltage (THD-U) or on the current (THD-I) is exceeded.
Solution:
The alarm system of the CX plus can react when the set limit values of the entire harmonic distortion
on the voltage (THD-U) or on the current (THD-I) is exceeded and it can switch off all active steps in
order to protect the capacitors. The limit values for the THD-U and the THD-I can be set individually in
the alarm system.
Procedure:
Set the THD-U limit value in the SETUP/502.
Set the limit value for the THD-U alarm in the SETUP menu 502.
Set the THD-I limit value in the SETUP/510.
Set the limit value for the THD-I alarm in the SETUP menu 510.
Activate the function “
Switch off steps one by one in case of TEMP alarm
” (SETUP/503).
Activate the function “
Switch off steps one by one in case of TEMP alarm
” (step switch-off
sequence) in the SETUP/503: SETUP/503 ==
YES
Delay time TEMP alarm / cycle step switch-off sequence (SETUP/504)
Set the delay time for the TEMP alarm in the SETUP menu 504. At the same time, this is also the
cycle for the step switch-off sequence.
Function:
Upon exceeding the THD-U or the THD-I limit value, the set delay time (SETUP/504) will run out first.
After the delay time has run out, the message
HarU
(THD-U alarm) resp.
HarI
(THD-I alarm) is
signalled on the display and the contact of the alarm relay is activated.
After the set delay time has run out again, the step switch-off sequence begins: In the process, the last
active step (AUTO, FON) is switched off first. All active steps (AUTO, FON) are switched off one by
one in the cycle of the set delay time, for as long as one of the two alarms is still active. All steps
which have been switched off by the alarm system are locked for 30 min. When all active steps have
been switched off, the control is stopped.
NOTE:
The alarm system does not switch off steps in manual operation. The step switch-off sequence
does not start until you leave the MANUAL menu.
If the THD-U and the THD-I fell below the set limit values, a still active step switch-off sequence is
cancelled. The control starts again and may switch steps on and off again. The steps which have been
switched off by the alarm system, however, remain locked for the duration of the blocking time and
thus are not available for the control.
If the function “Manual reset” (SETUP/501 = NO) is deactivated, the alarm messages (display and
alarm relay) are automatically reset after 15 s. The alarm relay is only reset, if no other alarm is active.
