Radiodetection T631 TDR User manual

T631 TDR
High Specification Coaxial
Cable Fault Locator
Operating Manual
Issue 6
Refer to Preface and Safety Instructions before operating
Radiodetection Ltd.
Western Drive
Bristol
BS14 0AF
United Kingdom
Tel: [phone]
Fax: [phone]
E-mail: [email protected] 00901209-6

© Radiodetection Ltd 2007. All rights reserved.
This document is copyright and may not be copied or reproduced or transmitted or modified or used, in whole or in part, in any
way whatsoever, without the specific prior written consent of Radiodetection Ltd.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 2

CONTENTS
Page
1. Preface & Safety 5
2. Introduction 7
3. Front Panel - Controls & Indicators 11
4. Power Sources 16
5. Display 19
6. Operating Modes 20
7. Operating Instructions 21
7.1 General 21
7.2 Switch On 21
7.3 Programming from the Help Menu 22
7.4 Setting Dielectric (PVF) 23
7.5 Connecting to cable under test 27
7.6 Locating a cable fault 27
7.7 Use of left hand cursor 28
7.7.1 Eliminating the length of the test lead 29
7.7.2 Measuring between two features 29
T631 OPERATING MANUAL 3
Radiodetection Ltd. 00901209-6

CONTENTS
Page
7.7.3 Resetting the LH cursor 30
7.8 Auto Fault Find 30
7.9 Return Loss Measurements 32
7.10 Filter 38
8. Use of the Memory 39
8.1 Storing a trace 39
8.2 Recalling a trace 39
8.3 Comparing a live and stored trace 39
8.4 Difference between a live and stored trace 40
9. RS232 Printing and PC Interface 41
10. Help Menu 43
11. Error Messages 44
12. Specification 45
13. Product Safety Data 53
Appendix – Bicotest Product Range 57
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 4

1. PREFACE & SAFETY
1.1 HEALTH AND SAFETY AT WORK ACT 1974 SECTION 6.1 (C)
Thisproductistestedandsuppliedinaccordancewithpublishedspecificationsand,whenused
in normal or prescribed applications and within the parameters specified, it will not cause
danger or hazard to health or safety.
All usage of the product must be in accordance with the Operating Manual for this equipment
and any work on the electrical components housed within the machine must be undertaken by
qualified personnel.
T631 OPERATING MANUAL 5
Radiodetection Ltd. 00901209-6

1.2 SAFETY PRECAUTIONS
Forconnectiontolivecablesupto600 VRMSusetheBicotestT631FBlockingFilter.
Only fit 2 Ah ‘C’size NiCad cells.
Do not charge the batteries when the ambient temperature is below 0°C.
AC adaptor and its carry pouch are not waterproof.
AC adaptor is for indoor use only.
The main unit is safe and conforms to IEC 1010. The AC adaptor conforms to the
manufacturers safety standards.
1.3 BATTERIES
The T631 is provided with a set of 2 Ah rechargeable NiCad cells. These are supplied in the
discharged state and must be charged for 24 hours before use. Charge the batteries as
describedinsection4.Note thatfull ratedcapacitymaynotbe achieved forthe firstthree cycles
of use.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 6

2. INTRODUCTION
The Model T631 is a pulse reflection (TDR) Cable Test Set, for locating cable faults and
evaluating changes in impedance caused by connectors, taps, terminations etc. Pulses
transmitted into a cable are reflected by cable imperfections. The transmitted pulse and the
reflectedpulse(s) are shownonthe display.Thetime takenbythe pulse totraveltothe faultand
return is a measure of the distance to the fault.Distance to faultis displayedon the screen after
the cursor is positioned to coincide with the start of the fault pulse. The type of fault can be
determined by analysis of the displayed waveform.
Althoughdesignedprincipally for50,75and93 Ωcoaxialcablesitisequallyeffectiveonothercable
types as a fault locator.
Impedance mismatches can be measured in terms of Return Loss (dBRL) with the location
displayed in feet, metres or time.
Principle features include a 15 location memory for trace storage with ability to transfer to a
printer or PC, and dual cursors for point to point measurements.
T631 OPERATING MANUAL 7
Radiodetection Ltd. 00901209-6

2.1 SAMPLE TRACES
1. Open circuit/high impedance series faults
Note: Positive (upward) reflection
2. Short circuit/low impedance shunt faults
Note: Negative (downward) reflection
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 8
Transmit Pulse Reflected Pulse
Transmit Pulse Reflected Pulse

The T631 will display:
a) A “live” trace.
b) A stored trace recalled from the memory.
c) A live and stored trace together for comparison.
d) The difference between a live and stored trace.
2.2 POWER SOURCE
The T631 is powered by 8 rechargeable cells in a compartment accessible from the rear of the
T631, or from an external DC power source via the DC jack.
When operated from batteries, the T631 will automatically switch off before the batteries are
completely discharged.
T631 OPERATING MANUAL 9
Radiodetection Ltd. 00901209-6

2.3 MAIN FEATURES
Figure 1 shows the front panel of T631.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 10

3. FRONT PANEL
3.1 CONTROLS
Switches the unit ON. To conserve battery life the unit will switch off 5 mins
after the last key operation. If automatically switched off all measurement
parameters will be restored when switched on again.
Switches the unit OFF. This will reset the instrument to the 6 m range, (or
equivalentinfeetortime),GainA1,2 nspulseandLINEmode.PVF,unitsand
impedance will remain as they were before switch off.
Rotary control to adjust the contrast of the screen display.It is recommended
that it is set to the mid position on switch on to obtain a display.
CURSORS – two independent cursors
Adjusts the position of the appropriate cursor. Cursors move left or right as
indicated.Ifhelddownthecursor initiallymovesslowlyand willthenaccelerate.
The cursor being moved is displayed as a solid line, the passive cursor is a
broken line.
T631 OPERATING MANUAL 11
Radiodetection Ltd. 00901209-6

PULSE WIDTHS
Enablesthevariouspulse widths availableon each rangeto be selected.The
pulse widths are either automatically selected (AUTO) or set to a specific
value (MANUAL) via the HELP menu.
HORIZONTAL EXPANSION (ZOOM)
Enablesthetraceaboutthesolidcursorto beexpandedbyfactorsof2,4and8,
dependingonrangeselected(seeSection7.7andSection12,Specificationfor
further details).
OPERATION
Selects the operating mode (see Section 6 for further details).
DIELECTRIC
Used to set the appropriate velocity factor for the cable dielectric.The value
willincrementordecrement.Ifhelddownthevaluechangesslowlyatfirstand
then quickens. Also act as numbers 6 and 11.
RANGE
Selects the displayed range.The range will increase or decrease and if held
down will step through the available ranges. Also act as numbers 7 and 12.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 12

SHIFT
Adjusts the vertical position of the live trace. If held down the trace shifts
– slowly at first and then quickens.Also act as numbers 8 and 13.
AMPLITUDE
Adjusts the vertical amplitude of the trace. If held down the unit will step
through the available gain stages.Also act as numbers 9 and 14.
MEMORY
Enablesa livetracetobestored intoanyof15 memorylocations.Alsoactsas
number 10.
Enables any of 15 stored traces to be recalled. Also acts as number 15.
BACKLIGHT
Switches the display backlight ON and OFF. The backlight will switch off
automatically after 5 minutes.Also acts as number 5.
T631 OPERATING MANUAL 13
Radiodetection Ltd. 00901209-6

INTERFACE
Calls up a menu from which the displayed trace and data may be transferred
toaprinter,or memorised waveformsmaybetransferredtoa PC,or reloaded
from a PC.Also acts as number 4.
AUTO FAULT FIND
Causes the unit to search for the next significant reflection, starting from the
right hand cursor position (see Section 7.8). Also acts as number 3.
HELP MENU
Accesses a “Help” menu for setting machine parameters (see Section 10).
Also acts as number 2.
RETURN LOSS
Enables the return loss between the transmitted pulse and a selected
reflected pulse to be determined. Also acts as number 1.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 14

3.2 CONNECTORS
Input/Output
BNC socket to connect to the cable under test.
9 way D connector to interface with a printer or PC.
DC jack to supply 12 – 20 V external DC.
Note centre is positive.
3.3 CHARGE INDICATOR
Battery Charging
Charge Indicator illuminates when the internal battery is being charged.
T631 OPERATING MANUAL 15
Radiodetection Ltd. 00901209-6

4. POWER SOURCES
4.1 INTERNAL BATTERY
4.1.1 RECHARGING
Thecellsmaybe rechargedbyconnecting theACadaptor tothe DCpowerjackand leavingthe
equipment switched off. The charge indicator will illuminate while the batteries are being
charged.Full charge is achieved in 14 hours. A fully charged battery will give approximately 8
hours operation if the backlight is not used. (see Section 12 ‘Power Source’ for details of
charging voltages).
Note:Whenfittingnewcellstheinitialchargeperiodshouldbe24hoursand14hoursthereafter.
4.1.2 MAXIMISING BATTERY LIFE
Do not recharge until the Battery Low warning is displayed.
Do not charge for more than 24 hours.
Stay within the RECOMMENDED temperature limits shown in the specification (Section 12).
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 16

4.1.3 REPLACEMENT
Figure 2 shows the rear view of the unit.
Cells are accessed by removing the back
cover which is secured by 2 fasteners.
See specification (Section 12) for cell type.
Itis recommended thatcellsare replaced as
a set of 8.
T631 OPERATING MANUAL 17
Radiodetection Ltd. 00901209-6
Figure 2 – Battery Access

4.2 EXTERNAL DC
Theunitwillrunfromanexternal12 – 20 VDCpowersourceviatheDCjack.Thismaybeeither
the AC adaptor or any other DC supply that meets the specification. Centre is positive.
Notethat the batteriesare charged when external15 – 20V DC poweris applied andthe
unit is switched off – DO NOT FIT NON-RECHARGEABLE BATTERIES.
4.3 MEMORY BACK UP BATTERY
The memory back up battery is a lithium manganese cell which is part of the main PCB
assembly.
The life expectancy is typically four years and replacement is recommended every two years
during a routine service to avoid possible loss of stored traces.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 18

5. DISPLAY
T631 OPERATING MANUAL 19
Radiodetection Ltd. 00901209-6
Figure 3 – T631 Display

6. OPERATING MODES
The unit has 4 display modes.
1. Line (L) thetraceobtainedfromthecableconnectedtotheBNCsocketisdisplayed.
2. Memory (M) the trace from a selected memory is displayed.
3. Dual (L & M) the trace obtained from the cable connected to the BNC socket and a
selected trace recalled from the memory are displayed simultaneously.
4. DIFF (L – M) thetracedisplayedisthedifferencebetweenthetraceofthecableconnected
to the BNC socket and a selected trace from the memory.
Radiodetection Ltd. 00901209-6
T631 OPERATING MANUAL 20