Protective Relay Design and Specifications
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Questions and Answers

What is the primary function of the protective relay in the system?

  • To prevent damage to the tap changer and transformer (correct)
  • To manage energy distribution to multiple devices
  • To monitor environmental conditions around the transformer
  • To enhance the efficiency of the transformer during operation
  • Which section is most likely to provide guidelines for the proper installation of the protective relay?

  • Energization of the Protective Relay
  • Technical Data
  • Special Designs
  • Mounting (correct)
  • What is the minimum oil flow required to trip the valve at 20°C for on-load tap-changers of Type E, F, G, K, R, T, G?

  • 0.8 m/s
  • 2.4 m/s (correct)
  • 1.0 m/s
  • 1.5 m/s
  • What kind of alterations does the manufacturer reserve the right to make?

    <p>Alterations that may differ in details from the delivered equipment</p> Signup and view all the answers

    Which feature of the housing ensures that water condensation is prevented in the terminal box?

    <p>Breather</p> Signup and view all the answers

    What voltage is required to test the relay's insulation to earth?

    <p>2.5 kV</p> Signup and view all the answers

    Which section likely details operational guidelines post installation?

    <p>Putting into Operation</p> Signup and view all the answers

    In terms of technical specifications, which aspect of the protective relay is crucial for ensuring its effectiveness?

    <p>Sensing mechanism accuracy and responsiveness</p> Signup and view all the answers

    What additional feature must a protective relay have when connected to the transformer?

    <p>It should immediately switch off the transformer when energized.</p> Signup and view all the answers

    What is most likely included in the 'Electrical connection' section?

    <p>Wiring diagrams and connectivity protocols</p> Signup and view all the answers

    What material is used for the housing of the relay?

    <p>Non-corrosive light alloy</p> Signup and view all the answers

    How many change-over contacts does the tripping switch contain?

    <p>One</p> Signup and view all the answers

    Which information is likely to be found in the Appendix?

    <p>Glossary of technical terms used throughout the document</p> Signup and view all the answers

    What is a potential design feature of the protective relay that aids in maintenance?

    <p>Built-in diagnostic testing capabilities</p> Signup and view all the answers

    What is the degree of protection rating for the housing of the relay?

    <p>IP 44</p> Signup and view all the answers

    What purpose do the two inspection glasses on the housing serve?

    <p>For flap valve position checking</p> Signup and view all the answers

    What is the protection type used for the protective relay (Ex)?

    <p>Oil immersion</p> Signup and view all the answers

    Which temperature classes are applicable for the protective relay on business premises subject to explosion hazards?

    <p>G1 and G4</p> Signup and view all the answers

    Which standard does the protective relay (Ex) comply with?

    <p>VDE 0171/1.69</p> Signup and view all the answers

    What is a potential application area for the protective relay (Ex)?

    <p>Business premises with explosion hazards</p> Signup and view all the answers

    Which of the following is NOT a design feature of the protective relay (Ex)?

    <p>Digital signal processing</p> Signup and view all the answers

    In which year was the protective relay documentation printed, according to the content?

    <p>2002</p> Signup and view all the answers

    The protective relay must be tested again after energization before putting the transformer into service.

    <p>True</p> Signup and view all the answers

    The maximum torque for connecting the leads to the terminal bolts is 10 Nm.

    <p>False</p> Signup and view all the answers

    It is advised to vent the protective relay when the transformer is filled with oil.

    <p>False</p> Signup and view all the answers

    When the flap valve is not in the 'Transformer off' position, the tripping circuit requires examination.

    <p>True</p> Signup and view all the answers

    The hood and terminal box cover of the protective relay should be locked using 3 screws.

    <p>False</p> Signup and view all the answers

    The tap changer insert should be put back into service immediately after inspection.

    <p>False</p> Signup and view all the answers

    The maximum torque for locking the hood is 7.5 Nm.

    <p>False</p> Signup and view all the answers

    Circuit breakers must allow the transformer to be switched on without pressing the protective relay's reset button.

    <p>False</p> Signup and view all the answers

    The primary function of the protective relay is to ensure compliance with environmental regulations.

    <p>False</p> Signup and view all the answers

    Installation guidelines are included in the section labeled 'Putting into Operation'.

    <p>True</p> Signup and view all the answers

    Protective relays are designed to operate effectively at temperatures above 50°C.

    <p>False</p> Signup and view all the answers

    The design of the protective relay includes features to facilitate easy maintenance.

    <p>True</p> Signup and view all the answers

    The appendix section offers specific information about warranty conditions.

    <p>False</p> Signup and view all the answers

    Modifications to the protective relay can occur without prior notice to the customer.

    <p>True</p> Signup and view all the answers

    The electrical connection section provides guidelines solely for safety-related wiring.

    <p>False</p> Signup and view all the answers

    Protective relays are only compatible with specific models of transformers and tap changers.

    <p>False</p> Signup and view all the answers

    The pipes from the protective relay to the oil conservator should have a nominal width of 30 mm to ensure proper operation.

    <p>False</p> Signup and view all the answers

    A protective relay should be installed in a vertical position to avoid erroneous responses from the mercury contact tube.

    <p>False</p> Signup and view all the answers

    The test push buttons of the protective relay must be located at the bottom of the housing.

    <p>False</p> Signup and view all the answers

    A stop valve is recommended to be installed between the protective relay and the oil conservator for safety.

    <p>True</p> Signup and view all the answers

    The tripping switch of the protective relay can only be connected as normally closed (n/c).

    <p>False</p> Signup and view all the answers

    To allow free escape of switching gas, the pipes connecting the protective relay should be inclined at 3 to 4 percent.

    <p>False</p> Signup and view all the answers

    For the protective relay to function effectively, it should not be exposed to transformer vibrations.

    <p>True</p> Signup and view all the answers

    The location of the arrow on the housing indicates the direction towards the transformer.

    <p>False</p> Signup and view all the answers

    Study Notes

    General Information

    • Protective relay prevents damage to tap changers and transformers, included in delivery.
    • Connection must ensure immediate transformer shutdown when the relay is energized.

    Technical Data

    • Outdoor housing design with IP 44 protection degree.
    • Relay control via flap valve with two drill hole sizes: 10 mm and 20 mm.
    • Compatible on-load tap-changers: Type A, M, V, H and Type E, F, G, K, R, T, G.
    • Minimum oil flow for tripping the valve at 20°C: at least 1.0 m/s for valve size 10 mm and 2.4 m/s for size 20 mm.
    • Tripping switch uses a mercury switching tube with one change-over contact.
    • Inrush and breaking current rating: 24...220 V a.c. and d.c., 2 amps (L/R = 25 ms).
    • Test voltage to earth requirement: 2.5 kV, 50 Hz, for 1 minute.
    • Weight is approximately 5 kg.

    Design Features

    • Housing made from non-corrosive light alloy with two flanges for pipe connections.
    • Flap valve position is visible through two inspection glasses located on the front and rear.
    • Tripping switch terminals housed in a terminal box, protected against oil.
    • Breather in terminal box helps prevent water condensation.
    • Flap valve diameter is labeled over the terminal box.
    • Two push buttons for checking tripping function and resetting the flap valve are covered by a hood.

    Special Designs

    • Protective Relay 1000 (Ex) available upon request at an additional cost.
    • Complies with VDE 0171/1.69 for explosion protection, suited for hazardous business environments.
    • Suitable for temperature classes G1 and G4, applicable to flammable materials.

    Appendix

    • Includes dimension drawing for Protective Relay RS 1000 (document code 8995660E).

    Cable Gland Installation

    • Fit the cable gland for leads with a diameter of 8 to 13 mm.
    • Close unused bore with a blind cover.
    • Connect leads to terminal bolts M5 with a maximum torque of 2 Nm.
    • Connect protective conductor to screw M6 (torque max. 5 Nm).
    • Lock hood and terminal box cover using 2 screws (wrench opening 13, max. torque 8.5 Nm).
    • Venting of the protective relay is unnecessary while transformer is filled with oil.

    Putting into Operation

    • Test the protective relay again according to section 5.1 before putting transformer into service.
    • Ensure circuit breakers trip transformer upon pressing "Trip" button.
    • Confirm transformers can only be restarted after the "Reset" button is activated.
    • Lock screws of terminal box cover and push button hood can be sealed.

    Energization of the Protective Relay

    • Determine energization time and tap changer operating position.
    • Check flap valve position; if not "Transformer off," examine the tripping circuit.
    • Remove tap changer insert for inspection as per instructions before reactivation.
    • Notify manufacturer or authorized rep if oil flow has affected flap valve position.

    General and Technical Data

    • Protective relay prevents damage to tap changer and transformer.
    • Test push buttons must be positioned for correct operation; "Transformer off" connects terminals 1 and 3, while "Transformer in operation" connects terminals 1 and 2.
    • Flap valve position must be monitored; improper installation may affect relay accuracy.
    • Ensure pipes to tap changer and oil conservator are 25 mm width, with a 1-2% incline for gas escape.
    • Install relay to mitigate transformer vibrations; include a stop valve between relay and oil conservator.

    Electrical Connection

    • Tripping switch can be configured as normally open (n/o) or normally closed (n/c).
    • Energization of the relay should immediately trip transformer circuit breakers.
    • Use threaded bore in terminal box for entering leads, selecting the most suitable side.

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    Description

    This quiz covers the technical specifications and design features of protective relays used in tap changers and transformers. Explore the important parameters such as housing design, valve control, and specific compatible tap-changer types. Test your knowledge on the proper functioning and requirements of these essential electrical components.

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