Appliance / Machine / Switchboard Safety
Glossary - Testing the safety of electrical appliances PAT TESTERS
Visual check Visual test of the equipment is intended to confirm that there are no visible signs of damage or defects. This can be re- corded on most of Metrel’s PAT testers for future reference.
Earth Bond / Continuity test Test to ensure that the earth cable has the ability to withstand a fault current in case a problem occur in the appliance. IT equip- ment can have problems with high current Earth Bond tests, in which case a soft cur- rent continuity test (20 ... 200 mA) can be performed to simply check if an earth path exists (for Class I appliances only).
Insulation test
A high DC voltage test to ensure that the in- sulation resistance between the phases (i.e. live and neutral) and earth is high enough to guarantee that equipment is safe to use.
Leakage test
The amount of current that finds an alter- native path back to the supply, other than through the neutral conductor. High leakage currents can cause both operation prob- lems (e.g. tripping RCDs) and health and safety issues (e.g. cause voltages to appear on pipework which can be a reason of in- jury). This test powers up the equipment with 230 V a.c. and measures the amount of leakage current the equipment produces.
Differential leakage
Differential leakage is measured in case an appliance has more than one connec- tion to ground (e.g. the metal housing of the appliance sits on the ground or is screwed down). A measure of the current passing through the cable may not be a true indication of the full leakage current supplied by the appliance. Differential leakage measures the difference in cur- rent between the live and neutral cable which provides a true value of how much current the appliance leaks to ground.
Substitute leakage In this test the live and neutral conduc- tors of the appliance are shorted togeth- er and a voltage of 40 V a.c. is applied between this point and either the earth conductor (class I) or the probe con- nected to any exposed conductive part (class I and class II). The test measures how much current passes from the live conductors into the test point.
Touch leakage
This test measures the amount of cur- rent that would pass through the human
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body if a person touched the appliance while it was in operation. The PAT test- er powers up the appliance and via the probe connected to the tested device simulates the average resistance of the Human body and measures how much current would pass through a person if he touched the appliance.
Polarity test
A polarity test checks that all the connec- tions in an IEC cable or extension cable are correctly fitted. Results include L-open, N- open, PE-open, L-PE shorted, L-N shorted, N-PE shorted, L-N crossed, L-PE crossed, N-PE crossed and multiple faults.
Flash test
Flash test is also referred to as Hi-Pot or Dielectric strength test. The test is a high AC voltage test which checks the dielectric strength of the insulation in a piece of equip- ment. This can be 1500 V for class I equip- ment and 3000 V for class II equipment and tends to be used in accordance with CE tests once an appliance has been repaired.
RCD test
This test checks how long it takes for a portable RCD to trip in the case that a fault occurs.
Project uploading
When retesting a site or location, pro- ject uploading allows previously saved information to be reloaded onto the PAT tester to speed up testing and enable trend comparison.
Autosequencing
Autosequencing is a series of tests that are initiated with the single press of a button and are automatically executed in a particular order by the test instrument.
Custom tests Custom tests allow the user to define the tests and times involved in the au- tosequence. This is extremely useful feature for testing unusual appliances or appliances that require a special meth- od of testing that is not included in the standard autosequences.
Trend comparison Trend comparison allows test informa- tion from different dates to be compared in order to discover if deterioration is oc- curring in an appliance. In case the de- terioration was found, the test engineer can make an informed decision as to if the frequency of testing and inspection is sufficient for the appliance.
MEASUREMENTS Continuity 200 mA Continuity 10 A Continuity 25 A
Insulation resistance 250 VDC Insulation resistance 500 VDC Differential leakage current Touch leakage current Substitute leakage current
Leakage current measurements with optional clamp Flash test PRCD testing
Polarity test (IEC lead test) Functional (load) test Voltage TRMS ADDITIONAL FEATURES PASS / FAIL evaluation Mains supply check Built-in Checkbox Graphical LCD
Graphical on-line help Backlight
Real time clock QWERTY keyboard
Auto testing (organizer, custom autotests)
Barcode shortcut auto testing Communication ports USB / RS232 / BLUETOOTH “Test and tag” (barcode scanner + label printer)
Data download to PC Project upload from PC Trend (compare) on instrument’s LCD Trend with PC SW PATLink PRO Plus Number of memory locations STANDARD / OPTIONAL ACCESSORIES Barcode scanner Label printer Receipt printer Basic PC SW Advanced PC SW GENERAL DATA Weight
Dimensions Part No.
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