Emerson Branson M1800 Instruction Manual page 14

per the Portable Appliance Testing (PAT) requirements, testing should be carried out by
the user.
Before doing the insulation testing, however, please read the following pertinent
information:
All of Branson's 220 V "C" and 230 V "E" units are equipped with Metal Oxide Varistors
(MOVs) as the primary components to absorb overvoltages in the power line. MOVs
disperse the over-voltage to the ground line and thus away from the equipment. Per their
mode of operation, these MOVs will cause the insulation resistance test to fail when it is
carried out at 500 V DC. As such, Branson recommends performing the test at a reduced
voltage (250 V DC), as allowed by the Code of Practice for In-service Inspection and
Testing of Electrical Equipment published by the IET (The Institution of Engineering and
Technology), as this will prevent the MOVs from triggering and failing the test.
4 100-214-294 REV. 05