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T&R Z-OVR Operating And Maintenance Manual

Cable impedance test system
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OPERATING AND MAINTENANCE MANUAL
Product:
Type:
DESIGNED AND MANUFACTURED BY:
T & R Test Equipment Limited
15-16 Woodbridge Meadows, Guildford, Surrey, GU1 1BJ, United Kingdom
Telephone:
01483 207428
Web: www.trtest.com
Cable Impedance Test System
Z-OVR
Software version 1.04
1
e-mail:
sales@trtest.com

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Summary of Contents for T&R Z-OVR

  • Page 1 OPERATING AND MAINTENANCE MANUAL Product: Cable Impedance Test System Type: Z-OVR Software version 1.04 DESIGNED AND MANUFACTURED BY: T & R Test Equipment Limited 15-16 Woodbridge Meadows, Guildford, Surrey, GU1 1BJ, United Kingdom Telephone: 01483 207428 e-mail: sales@trtest.com Web: www.trtest.com...
  • Page 2 GENERAL SAFETY STATEMENT CAUTION The following safety precautions should be reviewed to avoid injury to the user and damage to the product (and other products connected to it). To avoid potential hazards only use this product as specified.  Only suitably qualified personnel should use this equipment. Servicing of this product should only be carried out by suitably qualified service personnel.

  • Page 3: Safety Terms And Symbols

    SAFETY TERMS AND SYMBOLS The following safety symbols appear on the equipment: CAUTION/WARNING – Refer to manual Mains off Mains on The following safety symbols appear in this manual: This action or procedure may be dangerous if not carried out CAUTION correctly and may cause damage to the equipment or connected equipment.

  • Page 5: Table Of Contents

    CONTENTS DESCRIPTION OF EQUIPMENT Panel layout and functions 1.1.1 Control unit 1.1.2 Output unit 1.1.3 Display 1.1.4 Warning messages Installation 1.2.1 Environment 1.2.2 Supply requirements 1.2.3 Cables 14 1.2.4 System connections 1.2.5 Overload protection Functions 1.3.1 Output 18 1.3.2 Metering 1.3.5 Result storage THEORY OF OPERATION...
  • Page 6 Output Control Brushes Removal of the Z-OVR from Case STANDARD ACCESSORIES Spare Fuses Supplied: Standard Accessories Supplied: OVERALL PERFORMANCE SPECIFICATION 6.1. Insulation Resistance at 1000V DC 6.2. Applied Voltage Test 6.3. Accuracy of Instruments 6.3.1 Current metering 6.3.2 Voltage metering 6.3.3...

  • Page 7: Description Of Equipment

    DESCRIPTION OF EQUIPMENT The Z-OVR is a line/cable impedance measurement system for high voltage ac systems. The impedance of the line is measured by injecting a current and measuring the magnitude and phase angle of the voltage developed across the line. The resistance and reactance of the line are calculated from these results and displayed.

  • Page 8: Panel Layout And Functions

    Panel layout and functions 1.1.1 Control unit Figure 1.1 Z-OVR front panel...
  • Page 9 ITEM FUNCTION Output unit metering connection Metering/control connection to output unit Output circuit breaker Protection for control unit output Output unit power connector Power supply to output unit Mains input switch/circuit breaker Supply isolation switch and protection Mains inlet connector Mains supply connection Earth Terminal Terminal for optional connection to local...

  • Page 10: Output Unit

    1.1.2 Output unit Figure 1.2 Output unit front panel...
  • Page 11 75V 80A output socket Lowest voltage, highest current output. Note: push connector to release before pulling to remove plug from socket. Z-OVR metering connection Metering/control connection to control unit Power connector Power supply from control unit Protective earth terminal...

  • Page 12: Display

    1.1.3 Display The Z-OVR display simultaneously shows the injected test current, measured voltage and one of a number of other parameters depending on the position of the IMPEDANCE switch. For full details see section 1.3.4. Output current Phase angle Voltage input ¢...

  • Page 13: Installation

    – the unit must be allowed to cool. Caution Installation The Z-OVR control units and output unit are heavy. Avoid lifting where possible. Ensure that two people are used to lift the units and that appropriate manual handling techniques are used.

  • Page 14: Cables

    1.2.3 Cables The following cables are supplied with the Z-OVR system. Length Supply/interconnection cables Purpose Mains supply cable Supply to control unit Power interconnection cable Connects output unit to control unit Metering interconnection cable Connects output unit to control unit...
  • Page 15 Length Rating Output cables Purpose Output cable phase A Duplex lead fitted with Kelvin (red) clamp for overhead line CAT I connection. 300V* 12mm² current injection Max conductor size 80mm terminated in 6mm diameter. connector Warning 6mm² voltage sense terminated in 4mm shrouded plug Output cable phase B Duplex lead fitted with Kelvin...
  • Page 16 The phase clamp connections supplied with the unit are designed for connection to cylindrical conductors on overhead lines. An optional alternative set of phase leads is available for connection to other types of conductors and terminals using Kelvin clips as on the earth lead. Phase A Kelvin clip lead part number: AX136-0007 Phase B Kelvin clip lead part number:...

  • Page 17: System Connections

    1.2.4 System connections Figure 1.7 System connections...

  • Page 18: Overload Protection

    1.2.5 Overload protection Location Protection Mains supply Hydraulic-magnetic circuit breaker Control unit output Hydraulic-magnetic circuit breaker Control unit control/metering T4A HRC 32mm fuse Voltage input 2xT250mA HRC 32mm fuses Functions 1.3.1 Output The output has three ranges. The highest currents are available on the lowest voltage outputs. When testing, start with the lowest output voltage output.

  • Page 19: Metering

    1.3.2 Metering The Z-OVR is fitted with a true rms ammeter and voltmeter with hold facility. 1.3.2.1 Ammeter ranges ¢ 10.00A 90.0° 1.00V Figure 1.9 Ammeter IMPEDANCE Z=100.0m© X=100.0m© Four true rms current metering ranges are provided. The range is selected using the AMMETER switch on the control unit.
  • Page 20 Voltmeter range Resolution Accuracy Input impedance 10.00V 0.01V ±1%rdg±5d ~1k 30.00V 0.01V ±1%rdg±5d ~1k 300.0V 0.1V ±1%rdg±5d ~50k Always Use the 300V metering range if the test current is less than 5A. Accuracy note 1.3.2.4 Phase angle measurement ¢ 10.00A 90.0°...
  • Page 21 The impedance of the line under test is calculated from the voltage and current, considering the phase angle between them. The impedance, Z, and reactance, X, are displayed. The Z-OVR can measure impedance in the range 2m to 3000 in five ranges.
  • Page 22 Voltage Harmonics 3: 0.0% 4: 0.0% The Z-OVR can calculate the harmonic content of the output current and measured voltage. Select the harmonic to be displayed using the ADJ knob. Harmonics may be displayed up to 31st harmonic. Harmonic ranges are for indication only and are not calibrated.

  • Page 23: Result Storage

    Figure 1.16 Result storage The Z-OVR can store all displayed results to a standard USB memory key. The unit has a real- time clock and calendar so that all results can be time and date stamped. There are two stages to storing a result: firstly, typing in a comment, and secondly actually storing results.
  • Page 24 1.3.5.4 Folder structure The Z-OVR creates a folder on the memory key called TRTEST. Within this folder, a new folder is created for each day on which testing is carried out using the date as the folder name in the form DD-MM-YY (e.g.
  • Page 25 To select a results file to view, press . The results in the file may then be scrolled through using the ADJ knob. 1.3.5.6 Storing waveforms Figure 1.19 Store switch When WAVE is selected on the STORE RESULT switch, the voltage and current waveforms are written to the USB memory key in a CSV file when the output is switched off.

  • Page 26: Theory Of Operation

    THEORY OF OPERATION Kelvin connection The Z-OVR uses a Kelvin connection to remove the impedance of the current injection cables from the measured reading. Current is injected through a 12mm² core in the output cables and measured using a thinner core in the output cable.

  • Page 27: Impedance Testing

    Figure 2.2 Kelvin clamps Impedance testing Four separate impedance tests are carried out to characterise the impedance of a line or cable: 1. Phase A to phase B 2. Phase B to phase C 3. Phase C to phase A 4.

  • Page 28: Phase Reversal To Avoid Interference

    Figure 2.4 All phases parallel test (connections to control unit omitted for clarity) In each case a current in injected and voltage phase and magnitude is measured. The impedance, Z, is calculated from the rms current and voltage: Z=V/I The reactance, X, is calculated from the reactive power (Q) and the current. Q is in turn calculated from the real power (P) and VA (|S|).

  • Page 29: Operation

    Warning may cause arcing. The output unit output from the Z-OVR control unit is ONLY for connection to a T&R Test Equipment NLU75/80 output unit. Do not attempt to connect PCU1-SP loading units. The output unit provides isolation between the control unit and the line under test.

  • Page 30: System Connections

    3.1.1 System connections First connect the safety earth between the earth connection on the output unit and a suitable local earth. This should be a low impedance earth such as a substation earth bonding point or the base of the tower. A screw clamp is provided to make this connection. Connect the supply and metering leads between the control unit and the output unit.
  • Page 31 Figure 3.2 Phase A-B test Figure 3.3 Phase B-C test...
  • Page 32 Figure 3.4 Phase C-A test Figure 3.5 Parallel test to earth...

  • Page 33: Testing

    The table below gives the connections required for each test. Test Phase A to Phase B to Phase C to Parallel to phase B phase C phase A earth Lead Phase A high current lead 75V/150V/ Commoning 300V connected connected block Phase A voltage lead connected...

  • Page 34: After Testing

    After Testing On completion of the test, switch off the output using the OFF pushbutton. Return the output control to zero and switch off the supply. Before disconnecting the test-object, ensure the mains supply switch is in the OFF position.

  • Page 35: Maintenance

    Removal of the Z-OVR from Case To remove the instrument from its case, the following procedure should be used: - Remove the 14 socket head screws securing each of the side panels to the unit (each side has 4 screws to the rear, 4 screws to the front and 6 to each side).

  • Page 37: Standard Accessories

    STANDARD ACCESSORIES Spare Fuses Supplied: 1 off 32mm T4A HRC 10 off 32mm T250mA HRC Standard Accessories Supplied: 5m supply cable fitted with 32A CEE plug. 5m power interconnecting lead. 5m metering & control lead. Cable case to hold above leads. 10m safety earth lead.

  • Page 39: Overall Performance Specification

    OVERALL PERFORMANCE SPECIFICATION 6.1. Insulation Resistance at 1000V DC The insulation resistance will not be less than 10M between mains input to frame and all isolated outputs, and all combinations of isolated output to isolated output. 6.2. Applied Voltage Test Mains input to frame and all isolated outputs 2kVrms.

  • Page 41: Revision

    REVISION Product / Type: Z-OVR impedance system File: Z-OVR manual v1.doc Author: M. Clancy Issue / Date: 1 / 02.01.19 Checked By: Date: 28.01.19...
  • Page 42 Drawings Required A3/001778 latest issue (Z-OVR) A3/001770 latest issue (NLU75/80)

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