Related Manuals for GE MFAC 14
Summary of Contents for GE MFAC 14
- Page 1 GE Energy Connections Grid Solutions MFAC 14, 34 User Manual High Impedance Differential Relay Publication reference: R8007H...
- Page 3 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 circuits can cause serious damage, which often may not be immediately apparent but the reliability of the circuit will have been reduced. The electronic circuits of General Electric products are immune to the relevant levels of electrostatic discharge when housed in their cases.
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Page 4: Table Of Contents
TYPES: MFAC 14 MFAC 34 CONTENTS SAFETY SECTION INSTALLATION General Unpacking Storage Site COMMISSIONING Description of relay, calculation of setting and commissioning preliminaries Instructions to ensure that the relay can be commissioned at the specific settings for the application MAINTENANCE... -
Page 5: 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 6 Voltage and current connections should be made using insulated crimp terminations to ensure that terminal block insulation requirements are maintained for safety. To ensure that wires are correctly terminated, the correct crimp terminal and tool for the wire size should be used. 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.
- Page 7 Fibre optic communication Where fibre optic communication devices are fitted, these should not be viewed directly. Optical power meters should be used to determine the operation or signal level of the device. OLDER PRODUCTS Electrical adjustments Equipments which require direct physical ad ustments 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 electrical shock.
- Page 8 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 601010-1 : 1990/A2 : 2001 This equipment requires Class I a protective (safety) earth...
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Page 9: Installation
Section 1. INSTALLATION General 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. The relays are either despatched individually or as part of a panel/rack mounted assembly in cartons specifically designed to protect them from damage. -
Page 10: Commissioning
Description of relay, calculation of setting and commissioning preliminaries 2.1.1 Description of MFAC 14/MFAC 34 This is a voltage operated relay having seven equally spaced settings of 15–185 volts, 25–175 volts, 25–375 volts or 100–400 volts which may be selected by means of a plug bridge. - Page 11 The minimum knee point voltage must be ≥ The operating current of the relay is 38mA, irrespective of tap selected, excluding the current drawn by the external metrosil. When a standard metrosil is included with the relay, the relay operating current including the metrosil is given in the table below.
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Page 12: Instructions To Ensure That The Relay Can Be Commissioned At The Specific Settings For The Application
there is a small further movement of the armature. This ensures that contact follow through and wiping action is present. On units fitted with hand reset flag indicators, check the flag is free to fall before, or just as, any normally open contacts touch. Check that the external wiring is correct to the relevant relay diagram or scheme diagram. - Page 13 2.2.1 Test equipment required 1 – Secondary injection test equipment capable of providing an ac voltage supply of up to at least 120% of the relay setting. 1 – Multifinger test plug type MMLB 01 for use with test block type MMLG if fitted. 1 –...
- Page 14 2.2.5 Primary injection testing It is essential that primary injection testing is carried out to prove the correct polarity of current transformers. Before commencing any primary injection testing it is essential to ensure that the circuit is dead, isolated from the remainder of the system and that only those earth connections associated with the primary test equipment are in position.
- Page 15 Relay Metrosil Stabilising resistor (if fitted) Ammeter (in plug bridge circuit) Figure 1 Secondary injection of relay to check secondary operating current, setting voltage and relay operating current. Primary injection test set Relay Stabilising resistor (if fitted) Ammeter (in plug bridge circuit) Figure 2 Sensitivity check of restricted earth fault scheme by primary injection.
- Page 16 Primary injection test set Temporary connections Metrosil Relay Stabilising resistor (if fitted) Figure 3 Stability check of restricted earth fault protection. supply Temporary short circuit Relay Stabilising resistor (if fitted) Figure 4 Stability check on restricted earth fault scheme by back energising with a low voltage supply.
- Page 17 Temporary short circuit Isolating Generator links 87 Generator differential relay Voltmeter Figure 5 Testing sensitivity of generator differential protection using generator to supply primary current. Temporary short circuit Isolating links Generator 87 Generator differential relay A2 Ammeter Figure 6 Checking stability of generator differential protection.
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Page 18: Maintenance
With the armature closed onto a 0.011" feeler gauge the make contacts should be closed, but should be open using a 0.013" feeler gauge. Contact settings 2 contacts 4 contacts (MFAC 34) (MFAC 14) 20/25 grams 15/20 grams Force to just close the make contacts 15/20 grams... -
Page 19: Problem Analysis
Section 5. PROBLEM ANALYSIS Failure to operate Check diagram for correct input connections. Check tap voltage; this is marked above or below the plug bridge on the front of the module. Note: with the plug removed the relay setting goes to the highest tap value. Measure the input current at VS, this should be 38mA (excluding the metrosil). -
Page 20: Spares
Section 6. SPARES When ordering spares, quote the full relay model number and any component reference numbers, or briefly describe the parts required. Should the need arise for the equipment to be returned to General Electric for repair please fill in the RMA form at the back of this manual. A copy of any commissioning test results should also be sent with the equipment. -
Page 21: Commissioning Test Record
Section 7. COMMISSIONING TEST RECORD High Impedance Differential Relay Type MFAC Date Station Circuit. Relay Model No. Serial No. Setting range CT ratio Setting voltage Relay setting Type of ext. metrosil Shunt resistor ohms (if fitted) Calculated primary operating current Test results 2.2.3 Relay CT shorting switch... - Page 22 2.2.7 Stability check by primary injection Restricted earth fault Phases Primary current (A1) Spill current (A2) A–N B–N C–N Circulating current between two or more sets of current transformers. Phases Primary current (A1) Spill current (A2) A1–A2 B1–B2 C1–C2 Where more than two sets of current transformers are involved, injection should be carried out between set 1 and each other set in turn.
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Page 23: Repair Form
REPAIR / MODIFICATION RETURN AUTHORIZATION FORM – RMA FORM FIELD ONLY TO BE FILLED IN BY A GE GRID Automation REPRESENTATIVE Date : RMA Reference ACT Reference (M): Repair Center address to Ship the Unit: UK Grid Solution LTD St Leonards Building... - Page 24 5. Return Packaging Standards (ALL PRODUCTS) 1. Please ensure the device is clean, no sharp edges are exposed and the device is in a suitable condition to be handled. 2. Relay’s returned without cases should be placed in to Anti-Static Bags and sealed to protect hyper-sensitive components.
- Page 25 Imagination at work Grid Solutions St Leonards Building Redhill Business Park Stafford, ST16 1WT, UK +44 (0) 1785 250 070 www.gegridsolutions.com/contact © 2017 General Electric. All rights reserved. Information contained in this document is indicative only. No representation or warranty is given or should be relied on that it is complete or correct or will apply to any particular project. This will depend on the technical and commercial circumstances.