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General description
Megger’s Oil Test Sets are liquid dielectric breakdown
testers.
The OTS80PB, OTS60PB models are portable
instruments, designed for use in the field, where as the
OTS100AF, OTS80AF and OTS60AF are designed for
laboratory use.
They are fully automatic, powered by battery or mains
(model dependent) and facilitate accurate breakdown
voltage tests on mineral, ester and silicon insulating oils.
The precision test vessel sets the accuracy standard for
the liquid insulation test industry. For ease of use the
instrument comes pre-programmed with a ‘library’ of
international breakdown test standards and the ability
to create custom tests.
The instrument is housed in a metal case with moulded
end caps that accommodate convenient carry handles. The test chamber is designed with an easy-clean surface and
provides a drain for spilt oil through an internal pipe routed to the rear of the instrument. A beaker or similar can be
used for spillage collection. The test area is covered by a plastic lid with an electrically protective inner conductive layer
which, with the metal case, provides a safe equipotential enclosure for high voltage testing.
The lid allows in plenty of ambient light and users are able to view the test and witness stirring and the breakdown. The
chamber lid is dual redundant safety protected with micro-switches to prevent accidental electrification.
The advanced test vessel design yields highly accurate and repeatable results. Two stirring options are available; an
internal magnetic bean stirrer which is dropped into the oil and an optional lid mounted impeller that conforms to the
ASTM D 1816 standard. Stirring during breakdown testing is employed to produce an homogeneous distribution of
contaminants within the oil and to free any carbon generated between electrodes during testing.
Electrode gap is set by precision adjustment wheels that lock in position ensuring that the electrodes do not move
during a busy day in the field. It is, however, advisable to check the electrode condition and gap daily because it is a
critical parameter in breakdown voltage testing. Flat anodised Aluminium gap setting gauges are supplied in popular
sizes to facilitate electrode gap setting. Electrodes are detachable and are available in shapes that meet all international
standards, i.e. disk, spherical and mushroom (VDE) electrodes.
A selection of international breakdown tests are chosen from a library of standard sequences and started from the user
friendly menu on the LCD display. The top level test screen displays all pertinent test information to ensure the correct
electrodes are used with the specified electrode gap setting.
Results are viewed on screen and printed on either an external USB printer or the internal printer following a test result.
In the event of a breakdown not occurring before reaching the maximum voltage, the instrument will return maximum
voltage. This is a safety measure to ensure the instrument is not driven over its designed maximum voltage.
The instrument automatically turns off the display 15 minutes after completion of a test sequence or last use.
Safety features incorporated in the design include dual safety micro-switches and zero volt touch bar, the screened
chamber lid and convenient power supply On/Off switch. Pressing any button during a test will immediately remove the
high voltage and terminate the test. It is important to earth this instrument using the ground connection at the rear of
the instrument to ensure safe operation.
OTS PB models
The OTS60PB (60 kV) and OTS80PB (80 kV) oil test sets are small and the lightest on the market with weight ranging
from 16 kg to 23.5 kg depending on model configuration. They come complete with optional carry bag and transport
case. The carry bag has pouches for electrode accessory pack, leads, quick user guide, paper roll etc. These units can be
supplied mains powered only, or mains powered and battery operated for additional flexibility in portable applications.
The optional batteries are NiMH, or if selecting an 80 kV model a lead acid battery can be specified. In addition, an
internal 12 V DC charger and vehicle adaptor cable is standard when any battery option is fitted.
