Schaffner Group
User and Installation Manual
Ecosine
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9.2 Power capacitors
The power capacitors supplied with the filter modules are high quality components with an expected
lifetime of up to 100’000 hours (11 years). Nevertheless, their useful service life can be shortened by
electrical or thermal stress beyond their specification.
Power capacitor damage may also be caused by severe abnormal supply voltage peaks (i.e. lightning
– depending upon system protection) but may only be recognizable through the measurement of line
side harmonics distortion. This may be checked with a modern energy meter or by regular checkup
with a power quality analyzer. According to the above considerations, a 2 year inspection interval is
advisable.
Note:
an inspection should as well be performed after extreme overvoltage situations in the system.
9.2.1 Storage of capacitors
Up to 3 years-long storage, electrolytic capacitors can be operated without any restriction and the
nominal voltage can be applied without any preliminary preparation. System reliability and life-time ex-
pectancy are not affected.
On the other side, a longer (>3 years) storage of electrolytic capacitors without applying any voltage
can weaken the dielectric properties because of dissolution processes. The electrolytic solution is ag-
gressive, it can affect and weaken the dielectric in the timeframe between production and product
commissioning. The weak points are responsible for the higher leakage current shortly after the device
turn-on on site.
The residual current of electrolytic capacitors depends upon time, voltage and temperature. The resid-
ual current increases after long storage without applying voltage.
The amplitude of resulting residual current during unit commissioning can be up to 10 times larger on
short term. The capacitor’s residual current assumes the typical expected value at steady state for
nominal voltage.
During commissioning after long storage, it is recommended to restore the dielectric characteristics by
applying voltage progressively and with respect to the time frame the filters have been stored.
9.3 Electrical connections
Depending upon the environment and application, electrical connections, especially threaded bolts and
nuts, can degrade over time by means of losing their initial tightening torque. This holds true not only
for the filter, but for any such joint within an electrical installation.
Therefore, Schaffner recommends checking and tighten all electrical connections when a regular
scheduled maintenance of the entire device that incorporates the filter is ongoing.
Check of internal connections within the filters is not needed or should be conducted by a Schaffner
service representative.
