NPU, SW Version 1.8, ©ComAp, September 2003
NPU-1.8r2.PDF 10
Phase sequence supervision
Phase sequence supervision checks the right sequence. The angle has to be at interval (120° ± 30°)
among voltage vectors. The right phase sequence is L1→L2→L3. The LEDs L1, L2 and L3 are red flashing
at wrong phase sequence. If the voltage is too small (approx. <10% of rated voltage value) at any phase
then EEEE is displayed.
Frequency measurement
The frequency is measured in one phase. NPU selects the phase where voltage exceeds 10% of rated
value. If the voltage is not high enough sufficient in any phase then both LEDs
overfrequency/underfrequency are red flashing. The frequency cannot to be measured. In this case zero
delayed failure is evaluated.
Hint:
Previous error (red LED) indication is cleared when:
• No phase voltage is sufficient for measuring
• Phase sequence error is detected
Internal watchdog
To increase the operating safety the internal watchdog and parameters consistency checks are installed.
Flashing of LED ERR indicates NPU internal failure.
Check all adjusted parameters. If ERR is still flashing, send NPU for repair.
Output Relays
RE1 and RE4 are used mainly for proper adjusting and tests of NPU parameters. RE2 and RE3 are used
mainly for protection.
Relay RE1:
The relay RE1 opens at any new failure without delay. It closes after the time given by parameter B3.
Another failure during B3 time has no effect.
Relay RE2:
The relay RE2 opens at any failure with delay given by active protection (A8, A10, A14, A18, A20) see
table in the Chapter 6 – Displayed Quantities and Parameters. In example on the following drawing it is
Under voltage delay A18. RE2 opens immediately when Vector shift protection is activated. RE2 closes
after the time given by parameter B4. The relay doesn’t open (doesn’t indicate a new failure) until all active
failures are gone. LED ERR copies the state of RE2.
Relay RE3:
The relay RE3 opens at any failure with delay given by active protection (A8, A10, A14, A18, A20) see
table in the Chapter 6 – Displayed Quantities and Parameters. In example on the following drawing it is
Under voltage delay A18. RE3 opens immediately when Vector shift protection is activated. RE3 stays
opened until any failure is active and closes immediately when no failure is active or with delay B5 in the
case of vector shift protection.
Relay RE4:
The relay RE4 opens at any failure with delay given by active protection (A8, A10, A14, A18, A20) see
table in the Chapter 6 – Displayed Quantities and Parameters. In example on the following drawing it is
Under voltage delay A18. RE4 opens immediately when Vector shift protection is activated. RE4 closes
after the time given by parameter B3. The relay operates similar as RE2, but indicates any new failure.
This feature is available from software version 1.5 (see parameter B10 to find your software version).
Note:If there is no power supply, all relays are opened.
To Next Page
Loading...
Need help?
General
