Ask Alan
Alan Towler is Kewtech’s technical expert. Alan has worked for Kewtech from the beginning and is available to answer any technical questions that you may have. Here are some questions he has been asked recently:
For those instruments that have an auto null facility for taking into account the resistance value of the test leads and which is remembered even when the instrument is switched off, the auto null memory needs to be cleared and reset from time to time. For the Kewtech 64/65 products the procedure is below.
Switch on to continuity without the leads connected
Press the test button and lock down by turning it clockwise, >1999 is displayed
Press the F1 button - NULL OFF should now be displayed
Unlock the test button
This has now cleared the memory
Switch OFF
Switch ON and plug the test leads into L (brown) and PE (green)
Short the tips together
Press and lock down the test button
Press the F1 button and NULL √ should be displayed
PLEASE NOTE*
This procedure is good practice and advisable to be carried out when you change from prods to croc clips and vice versa
For the KT64/65 Do not use anything other than a 500mA F 600V ceramic fuse in the battery compartment. Before carrying out a continuity / insulation test it is imperative to carry out a voltage check to establish whether voltage is present or not.
On early versions of the KT64, if you switch from a live test to a dead test, whilst still connected to a live circuit with the test button locked down you will blow the 500mA Fuse. On the latest versions of the KT64 (and all KT65s) a unique constant monitoring feature prevents the fuse from blowing, a warning is simply given.
No, the use of the check box is to ensure that your instruments do not drift away from their specification between calibrations. You should produce a calibration and regular check policy with consideration to how much use your instruments get, are they used by dedicated personnel or are they in a pool and many users test with them, the conditions in which they are used and previous experience concerning the accuracy of readings.
The KT64 has a high specification insulation range (2000MΩ) even at the 500V test setting. So in some circuits where there is a very small leakage the tester will very quickly climb beyond 1000MΩ and then take some moments to settle. Most other instruments only go up to 1000 MΩ so would display >999 MΩ. In the case of the KT64 if the reading is greater than 1000 MΩ and is taking time to settle, it is legitimate to record >999 MΩ, before waiting for it to settle.
