CIRCUTOR FRE Series - Manual (Page 15)

FRE / FRES
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7 MAINTENANCE
7.1 Safety regulation
SAFETY
Apply the safety regulations listed in section 2 of this manual before operating the
equipment.
The standards and applicable national laws of the country where the capacitor bank with
FRE filters is installed or operated should be strictly followed.
7.2 Maintenance with the filter bank disconnected
7.2.1 Basic maintenance protocol
Monthly
• Visually inspect the capacitors
• Check the protection fuses
• Control the environment temperature (average must be about 30 ºC. in accordance with IEC 60831 ).
• Control the supply voltage (especially during moments of low load, it must not exceed the nominal
value +10%).
• Check the temperature of thyristor's heat sinks. It must be less than 80ºC
Every six-month
• Keep the capacitor terminals and reactors clean.
• Force all steps off (push down key at PF regulator front plate). Once all disconnected, check that the
current drawn by the three phases is practically zero. If significative current is detected in any phase
indicates that there is a shorted thyristor.
• Check that the current at each step and each phase is not less than 25% neither greater than 120%
of the nominal value. Unbalance between phases must be less than 15%.
Annually
• Perform isolation tests on the different elements of the power circuit, applying 2.5 kV during 1s
between passive components (basically L and C) and ground terminal.
NOTE: To carry out isolation tests, thyristors must be short-cutted.
• Check the capacity of the different steps. An indirect verification can be performed by checking that
the consumption matches the value stated in Table7-4, with a maximum deviation of ± 10%.
• Check the tightness of all terminal connections on the different power elements.
• Inspection of the fuses.
- Power circuit: NH fuses. Check continuity and temperature.
- Control Circuit: Neozed fuses or circuit breaker. Check continuity and temperature.
7.2.2 Tightening the electrical connections.
• The connections must be tight. The tightening torques for different elements of the filter banc are
listed in Table 7-1, Table 7-2 and Table 7-3
Table 7-1.- Tightening torques of cables fuses and to thyristors
Device TORQUE (Nm)
NH-00 fUSES 15,2
Power circuit of thyristors 3,25
Thyristor to heatsink clamping 5
7.2.3 Key points for inspecting static switches.
• Check that the plastic parts are not blackened and do not show signs of burning or hardening.
• Check the tightness of cables and terminals, as shown in Table 7-1
• The terminals must be clean.