Melitta LOOK Operating Instructions Manual
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Melitta LOOK Operating Instructions Manual

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Service Manual
Type MVTU
Definite Time Delayed Relays

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Summary of Contents for Melitta LOOK

  • Page 1 Service Manual Type MVTU Definite Time Delayed Relays...
  • Page 3 Service Manual Type MVTU Definite Time Delayed Relays HANDLING OF ELECTRONIC EQUIPMENT A person's normal movements can easily generate electrostatic potentials of several thousand volts. Discharge of these voltages into semiconductor devices when handling electronic circuits can cause serious damage, which often may not be immediately apparent but the reliability of the circuit will have been reduced.

  • Page 4: Table Of Contents

    TYPES: MVTU 11 Definite Time Delayed Undervoltage Relay MVTU 12 Definite Time Delayed Overvoltage Relay MVTU 13 Definite Time Delayed Neutral Displacement Relay MVTU 18 Definite Time Delayed Neutral Displacement Relay with Additional Timer CONTENTS SAFETY SECTION DESCRIPTION OF SETTINGS Voltage settings Time settings Trip indication...
  • Page 5 MAINTENANCE Visual inspection Functional checks PROBLEM ANALYSIS Test equipment required for fault finding General procedure and precautions Inspection – removal of module from case Connections for MVTU 11, MVTU 12 and MVTU 13 Checking voltage supplies to module Printed circuit board tests 6.6.1 Monitoring of the voltage across relay coil 6.6.2...

  • Page 6: Safety Section

    SAFETY SECTION This Safety Section should be read before commencing any work on the equipment. Health and safety The information in the Safety Section of the product documentation is intended to ensure that products are properly installed and handled in order to maintain them in a safe condition.
  • Page 7 Before energising the equipment it must be earthed using the protective earth terminal, or the appropriate termination of the supply plug in the case of plug connected equipment. Omitting or disconnecting the equipment earth may cause a safety hazard. The recommended minimum earth wire size is 2.5 mm , unless otherwise stated in the technical data section of the product documentation.
  • Page 8 Older Products Electrical adjustments Equipments which require direct physical adjustments to their operating mechanism to change current or voltage settings, should have the electrical power removed before making the change, to avoid any risk of electric shock. Mechanical adjustments The electrical power to the relay contacts should be removed before checking any mechanical settings, to avoid any risk of electric shock.

  • Page 9: Technical Specifications

    Technical Specifications Protective fuse rating The recommended maximum rating of the external protective fuse for this equipment is 16A, Red Spot type or equivalent, unless otherwise stated in the technical data section of the product documentation. Insulation class: IEC 61010-1: 1990/A2: 1995 This equipment requires a Class I protective (safety) earth...

  • Page 10: Description Of Settings

    Section 1. DESCRIPTION OF SETTINGS Voltage settings The setting voltage is determined by the positions of the six dual-in-line switches. The sum of all the voltages shown by each respective switch position and the constant value gives the required setting voltage. For example, an MVTU 11 with the switches set to the position shown corresponds to a setting of 32 + 26 = 58V ac.

  • Page 11: Mvtu 11 Undervoltage And Mvtu 12 Overvoltage

    MVTU 11 Undervoltage and MVTU 12 overvoltage Relay ac Relay dc Resistor assembly Dropper resistor values fitted: rating (V) rating (V) part number 50/60Hz dc series ac series resistor (ohm) resistors (ohm) Rext 1 Rext 2 57/70 30/34 None required —...

  • Page 12: Installation

    Section 3. INSTALLATION Precautions Protective relays, although generally of robust construction, require careful treatment prior to installation and a wise selection of site. By observing a few simple rules the possibility of premature failure is eliminated and a high degree of performance can be expected.

  • Page 13: Commissioning Tests

    Section 4. COMMISSIONING TESTS Note: Earlier relays were fitted with hand reset mechanical flag indicators, later relays being fitted with a non-volatile hand reset LED trip indicator. CAUTION: If a flag indicator is fitted, damage is likely to be incurred if the flag indicator/ armature assembly of a miniature relay is actuated manually with a screwdriver/ probe.

  • Page 14: Functional Testing

    Functional testing Equipment required (all versions): Variac transformer DC voltmeter to check nominal dc volts AC voltmeter to cover setting range Resistance meter AC ammeter 0-10mA One double pole switch One electronic timer MVTU 11 and MVTU 12 380/440V versions only: Step-up transformer to cover setting range of 380/440V relay MVTU 13 and MVTU 18: One 6W 50kΩ...

  • Page 15: Voltage Setting Check

    4.5.4 Voltage setting check The pick-up and drop-off voltages of the relay should be measured with the timer set to 0.1s and with the voltage setting switches set to each of the positions shown in the table below. 1 = switch closed (left hand position) 0 = switch open (right hand position) Table 1 Switch position...
  • Page 16 Start timer Stop REXT 2 timer Step-up Transformer Figure 2 Test circuit for the 220/250V and the 380/440V versions of MVTU 11 and MVTU 12 Start timer Stop timer Figure 3 Test circuit for 380/440V version of MVTU 11 and MVTU 12 when no step-up transformer is available MVTU 11 undervoltage relay See Figure 1 for the test circuits for the 57/70V and 100/120V versions and Figure...
  • Page 17 Repeat the test for each of the settings shown in Table 1. The allowable errors on the voltage settings are ±2% on the lowest setting and ±4% on all other settings (no allowance has been made for instrument errors). The drop-off value should be within 5% of the pick-up value. MVTU 12 overvoltage relay See Figure 1 for the test circuits for the 57/70V and 100/120V versions and Figure 2 for the 220/250V and the 380/440V versions.

  • Page 18: Timer Setting Check

    Setting voltage Pick-up voltage at relay input Test number terminals (27 & 28) (V) MVTU 11 MVTU 12 MVTU 11 MVTU 12 1 ± 1 2 ± 1 2 ± 1 4 ± 1 3, 4, 5 Z + 10 ± 2 Z + 17 ±...

  • Page 19: Final Setting Checks

    MVTU 18 – neutral displacement Time delay t is checked as for MVTU 13 Time delay t is checked by connecting the timer as shown in Figure 4 and repeating the tests as for time delay t Start Stop timer timer T1 Start timer...

  • Page 20: Maintenance

    Section 5. MAINTENANCE Periodic maintenance is not necessary. However, periodic inspection and test is recommended. Visual inspection Isolate all supplies and withdraw the module from the case using the two black handles on the relay. Inspect the printed circuit board for any sign of loose components or connections.

  • Page 21: General Procedure And Precautions

    General procedure and precautions Care must be taken when making test connections to printed circuit boards to avoid short circuiting or damaging the copper tracks. Before connecting or disconnecting any test equipment the relay must be isolated from the supply. Relevant schematic diagrams MVTU 11 –...

  • Page 22: Checking Voltage Supplies To Module

    PCB ZJ0065: Connection 1 to terminal 13 positive dc supply Connection 2 to terminal 14 negative dc supply Connections 3, 4, 9 and 10 to pcb. ZJ0160 Connection 5 to terminal 27 – ac input Connection 6 to terminal 28 – ac input Connection 7 to pcb screen PCB ZJ0160: Connections 1, 2, 3 and 4 to ZJ0065...
  • Page 23 An ammeter should be connected in the positive supply line to measure these burdens. Typical values for the dc burdens are shown in the following tables for the MVTU 11, 12, 13 and 18. Burdens for MVTU 11 definite time delayed undervoltage relay Nominal voltage range (V) 30/34 48/54...
  • Page 24 Burdens for MVTU 12 definite time delayed overvoltage relay Nominal voltage range (V) 30/34 48/54 110/125 220/250 Series dropper resistor None 2 x 4k7 Rext 1 (ohm) in parallel DC voltage supplied for test (V) Relay on Current drain standby for relays Vin <...
  • Page 25 Burdens for MVTU 13 definite time delayed neutral displacement voltage relay Nominal voltage range (V) 30/34 48/54 110/125 220/250 Series dropper resistor None 2 x 4k7 Rext 1 (ohm) in parallel DC voltage supplied for test (V) Relay on Current drain standby for relays Vin <...

  • Page 26: Measurement Of The Ac Operating Currents Of The Modules

    6.6.3 Measurement of the ac operating currents of the modules Monitor the ac input current by connecting an ammeter in series with one input terminal and the source. This test should be done at the following input voltages: 63.5V 57/70V version of MVTU 11 &...

  • Page 27: 6.10.1 Setting Up Procedure For The Flag Assembly

    To gain access to the flag assembly, to replace parts or check the settings, it is necessary to dismantle the module. Once access to the flag assembly, mounted on the front plate of the relay, has been gained, adopt the following procedure: Remove the screw holding the side plate to the top plate and remove the side plate.

  • Page 28: 6.10.2 Flag Replacement Parts

    6.10.2 Flag replacement parts Spring GT7001 001 Flag GT9009 001 Clamp plate GT2007 001 Printed circuit board ZG0859 Armature clip Several different makes of relay are used, which require different designs of armature clip. When ordering a replacement relay, state that it is for use in a flag assembly and it will be supplied with the correct armature clip.
  • Page 29 Phase rotation (See Note 3) Rext(2) Output (See Note 6) circuits RL1-1 Case earth Rext(1) Power supply (See Note 4) Output circuits contacts Reset RL1-2 secs Case earth connection (See Note 2) Notes: 1. (a) CT shorting links make 5. Contacts RL1-1 and RL1-2 are shown in the de-energised before (b) and (c) disconnect.

  • Page 33: Commissioning Test Record

    Section 7 COMMISSIONING TEST RECORD Definite Time Voltage Relays Type MVTU Date Station Circuit Relay Model No. MVTU Serial No. Rated AC Voltage Vn Rext 2 (if required) DC Auxiliary Voltage Vx Rext 1 (if required) DC Supply Check Volts Voltage Setting Check Timer Setting = 0.1 s Voltage Setting...
  • Page 34 Timer Setting t Check MVTU 18 only Voltage Setting Vs Final Setting Ts Time Contact Check (All Relays) MVTU 18 only Trip Indicator Check Operate 9-11 8-10 Reset 10-12 ______________________________________ _______________________________________ Commissioning Engineer Customer Witness ______________________________________ _______________________________________ Date Date...

  • Page 35: Repair Form

    REPAIR FORM Please complete this form and return it to ALSTOM T&D Protection & Control Ltd with the equipment to be repaired. This form may also be used in the case of application queries. ALSTOM T&D Protection & Control Ltd St.
  • Page 36 What did happen? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ When did the fault occur? Instant Yes/No Intermittent Yes/No Time delayed Yes/No (Delete as appropriate). By how long? ___________ What indications if any did the relay show? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________ Was there any visual damage? ____________________________________________________________________________ ____________________________________________________________________________ ____________________________________________________________________________...
  • Page 40 A L S T O M T & D P r o t e c t i o n & C o n t r o l L t d St Leonards Works, Stafford, ST17 4LX England Tel: 44 (0) 1785 223251 Fax: 44 (0) 1785 212232 Email: enquiries@pcs.alstom.co.uk Internet: www.gecalsthomgpc.co.uk...

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