Introduction - Megger BTDR1500 Guia Del Usuario

2.0 INTRODUCTION

Thank you for purchasing this quality Megger product. Before attempting use of your new instrument please take the time to read this user guide,
ultimately this will save you time, advise you of any precautions you need to take and could prevent damage to yourself and the instrument.
The Megger BTDR1500 is an advanced instrument capable of identifying a wide range of cable faults. It incorporates an Insulation Tester, a DC
Voltmeter, Time Domain Reflectometer (TDR) and a Digital Bridge to allow for the accurate location of short and open faults on a cable.
The Voltmeter measures a DC voltage to ± 250 V and can verify if a telecomm cable has a Telecomm Network Voltage (TNV) present on it.
The TDR has a range of 10 m to 3000 m. It transmits a narrow pulse of electrical energy along a pair of conductors within a cable and times how long
any reflections of the pulse take to get back. By knowing how fast these pulses travel through a given cable, the measured time can be converted to a
distance to fault. The reflections are caused by impedance changes within the cable that are significantly different from the characteristic impedance of
the cable. A partial to full short circuit will have a negative going reflection whereas a partial to full open circuit will have a positive going pulse. If the
change in impedance is less significant, the ability to discern the cable feature accurately using the TDR technique alone can be difficult and so the
Megger BTDR1500 provides a Digital Bridge for this occasion.
The Digital Bridge can measure the insulation resistance up to 200 MΩ (insulation test), the loop resistance up to 2 kΩ (2-wire loop test) and the series
leg resistance of up to 1 kΩ (3-wire loop test). Where a fault causes the insulation resistances to lie below 20 MΩ, the fault position can be determined
(AUTO test) relative to the meter end and also relative to the far end where a loop has been made by fitting a strap between the wire under test and
one or two return wires. In the case of a single return wire (2-wire test method), the position of the strap is assumed to be at the position of half the total
loop resistance. If two return wires can be used (3-wire test method) the position of the strap will be known to greater accuracy and will be independent
of the resistance of either of the return wires.
5