Principle of Measurement – Ramp
During RCD Ramp testing, the earth leakage current starts at 20% of RCD rated
current and increases by 10% of RCD rated current every 300ms up to a maximum
of 110%. For example a 30mA Ramp test runs from 6mA to 33mA.
The trip time is measured as in the normal case and the trip level calculated from it.
RCD Test Function
Caution
Although fully protected against over voltage to 550VAC this tester should only be
used on a 230V supply.
The Socket & See MFT5000 will test all the most commonly encountered Standard
and Selective type AC and Type A RCDs across the full range of tests required by
BS 7671.
Test Requirements
Each RCD is tested to ensure that:
• It is not prone to ‘nuisance’ tripping as does not trip when a fault of half its
rated current is introduced. This is referred to as the x½ test.
• It operates with a maximum disconnection time of 300ms (AC / A type)
when a fault at its rated current is introduced. This is referred to as the x1
test.
• In the case of an RCD rated at 30mA it is tested to ensure that it operates
with a maximum disconnection time of 40ms when a fault of five times its
rated current is introduced. This is referred to as the x5 test.
For the reasons explained below all of the above tests have to be conducted at
both 0° and 180° this means that four tests (or for 30mA RCD’s six tests) have to be
made for each RCD.
The user friendly design of the Socket & See MFT5000 simplifies the test process
by enabling you to do any of these tests by making just two function selections.
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