8
Type VFI, Fluid-insulated Switchgear
INSTALLATION, OPERATION AND MAINTENANCE INSTRUCTIONS
MN285006EN March 2018
To assure trouble-free operation of this equipment, a
regular schedule of fluid testing and fluid maintenance is
required. A routine fluid testing and maintenance schedule
is necessary to monitor changes that occur in the fluid
as a result of normal operation and to detect abnormal
conditions that may occur.
Maintaining a record of this test data will help in assessing
the condition of the fluid over time.
Frequency of maintenance
Fluid insulated units
The insulating fluid should be initially tested within two
years after the installation of the equipment. That test will
yield information required to establish a baseline reference
for observing trends in the unit’s normal operation and to
diagnose any fault conditions that may be present.
After the initial fluid testing and inspection, vacuum
switchgear should be maintained every two years.
Each scheduled maintenance of the switchgear should
include a physical inspection of the unit, a fluid level check,
and fluid testing as described in the
Fluid testing
section of
this manual.
Types of fluid samples
The unit must be de-energized before withdrawing a fluid
sample. Withdrawing a fluid sample from a unit that has
critically low fluid level could result in flashover and unit
failure when the unit is re-energized. Never energize this
equipment without ensuring that it is filled to the proper
fluid level with clean, dry insulating fluid.
The fluid sampling procedure requires that two types of
fluid samples be taken:
1 . A bulk fluid sample
for general fluid tests.
Approximately one quart (one liter), taken in accordance
with ASTM D923 (latest revision), is required.
2 . A “gas-tight” fluid sample
, taken in accordance with
ASTM D3613 (latest revision), for diagnosis and fault
gas analysis
Fluid sampling guidelines
WARNING
Hazardous voltage . This equipment must be
de-energized and grounded prior to conducting any
maintenance, dielectric fluid processing or dielectric
fluid filling procedures . Failure to comply can result in
death or severe personal injury .
T239 .2
Use the following fluid sampling guidelines to prevent
contamination and to safely extract fluid samples:
1. De-energize and ground the switchgear prior to
sampling fluid.
2. Where local governing authorities allow access to
energized equipment, the following precautions must
be taken:
DANGER
Hazardous voltage . Contact with hazardous voltage will
cause death or severe personal injury . Follow all locally
approved safety procedures when working around high-
and low-voltage lines and equipment .
G103 .3
WARNING
Hazardous voltage . Always use a shotgun stick when
working with this equipment . Failure to do so could
result in contact with high voltage, which will cause
death or severe personal injury .
G108 .0
a. A hotstick tool capable of uncapping, opening and
collecting fluid from the fluid sampling valve should
be used to keep personnel away from the energized
bushings.
WARNING
This equipment is not intended to protect human
life . Follow all locally approved procedures and safety
practices when installing or operating this equipment .
Failure to comply can result in death, severe personal
injury, and equipment damage .
G102 .1
b. Personnel authorized to access energized equipment
must be properly trained in locally approved safety
procedures and utilize locally approved personal
protection equipment.
WARNING
Do not operate this equippment if energized parts are
not immersed in dielectric fluid . Operation when parts
are not properly immersed in dielectric fluid may result
in internal flashovers that will damage the equipment
and can cause death or severe personal injury .
G104 .4
c. Check switchgear fluid level prior to extracting a
fluid sample. If the fluid level is low, do not attempt
to extract a sample.
d. A means to plug the fluid sampling valve should be
available in the event the valve is unable to close
and fluid continues to flow.
WARNING
The switchgear tank must have neutral or positive
internal pressure prior to extracting a fluid sample .
Negative internal pressure may cause air to enter the
tank during sampling which can reduce the fluid’s
dielectric strength . This may result in internal flashovers
that will damage the equipment and can cause death or
severe personal injury .
e. Neutralize internal tank pressure by pulling on the
pressure relief device ring prior to opening the
sampling valve.
