ELECTRICAL PROTECTION AND INSTRUMENTATION

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13.1 ELECTRICAL PROTECTION RELAYS AND INSTRUMENTATIONS
Whether or not specified in the Bill of Quantities and/or Drawings, the following generator set electrical protection relays and their associated current transformers and electrical measuring instrumentations shall be provided and installed at the generator set switchboard. For generator set of rated capacity at and exceeding 1000 kVA and for generator sets in parallel operation mode, the electrical protection relays and instrumentations shall be of microprocessor based numeric type as specified herein in Section 13.2 – Generator Protection Relays. Otherwise, the protection relays and electrical measuring instrumentations shall be of digital type. Electrical protections for the generator set shall include but not limiting to the followings:-
(1) Over current with inverse-time operating characteristic;
(2) Earth fault, instantaneous characteristic;
(3) Restricted earth fault for the neutral, instantaneous characteristics for generator set rated at 1000 kVA and above. The operation of this relay shall also cause to shut down the engine;
(4) Restricted earth fault for the alternator stator windings, instantaneous characteristics for generator set rated at 1000 kVA and above. The operation of this relay shall also cause to shut down the engine;
(5) Over-excitation detection based on volts/hertz measurement for generator set rated at 1000 kVA and above. The operation of this relay shall also cause to shut down the engine;
(6) Over/under-voltage for generator set rated at 1000 kVA and above and for generator sets in parallel operation mode. The operation of this relay shall also cause to shut down the engine;
(7) Synchronising check relays for both manual and automatic synchronisation for generator sets in parallel operation mode. The operation of this relay shall cause to open or prevent the closing of the generator set circuit breakers;

(8) Over/under-frequency for generator set rated at 1000 kVA and above and for generator sets in parallel operation mode;
(9) Reverse power for generator sets in parallel operation mode;
(10) Voltage phase reversal for generator sets in parallel operation mode.

 

The operation of the electrical protection relays shall cause the generator set circuit breaker to trip. Measuring instrumentations with LED display shall include:-
(1) Voltmeters (R-phase; Y-phase; B-phase);
(2) Ammeters with maximum indicator (R-phase; Y-phase; B-phase);
(3) Frequency Hz meter;
(4) Hour-run meter;
(5) Power factor meter;
(6) Kilo-watt-hour meter;
(7) Active power meter for generator set rated at 1000 kVA and above and for generator sets in parallel operation mode;
(8) Reactive power meter for generator set rated at 1000 kVA and above and for generator sets in parallel operation mode;
(9) Combined synchroscope and synchronizing check relays of LED type for generator sets in parallel operation mode;
(10) Dual frequency meter for generator sets in parallel operation mode;
(11) Dual voltage meter for generator sets in parallel operation mode.

 

The Electrical Contractor shall ensure and verify with simulation tests and function checks for the operations of each electrical protection relays in the presence of the S.O’s Representative during switchboard factory acceptance tests and also during testing and commissioning at site upon completion of the generator set erection. All tests shall be
carried out and recorded, and test results shall be submitted to S.O.’s Representative

 

13.2 GENERATOR PROTECTION RELAYS
Notwithstanding specified above or elsewhere, the generator protection relays for the generator set rated capacity at and exceeding 1000 kVA and for generator sets in parallel operation mode shall be microprocessor based numerical relays with the microprocessor deciding on alarm and trip conditions. Relays shall be of approved type complying with relevant part of IEC 60255, and shall be suitable for use in a tropical climate with an operating temperature range of up to 70 0C and a relative humidity of 90 %. The rated operating voltage of the relays shall 120 Vac – 270 Vac or
16 Vdc – 250 Vdc. The relays shall incorporate surge protective device against voltage surge. There shall be an LED indicating a healthy power supply on the power supply module.
All settings, date, time and fault records shall be stored in non-volatile memory. The settings shall be stored in Electrically Erasable Programmable Read Only Memory (EEPROM). It shall be possible to change the relay settings in the foreground without affecting the actual operating values in the background. This shall make it possible to
change the settings on a live circuit breaker, taking the new set values in use only after a final confirmation is done. Upon inception of fault, the protection device shall capture the fault data. Continuous self-supervision for internal faults on the protection modules and the control modules shall be available. The self-supervision shall inhibit any tripping from occurring if an internal fault is detected and provide an indication for alarm. Relays shall also be provided with a provision for manual operation of supervision function as to be able to check the relay as and when required. The relays shall have RTD (Resistance Temperature Device) input module to provide the following: –
(a) Thermal model biasing;
(b) Temperature alarm and trip; and
(c) RTD open or short indication

Protection and control modules shall have NUMERICAL displays from which settings, currents, memorised fault values and relay operation shall be displayed. Relays shall also have LED indicators for identification of fault on each phase. All measured values (i.e. phase currents) and fault values shall be displayed in its primary values. The relays shall have SERIAL COMMUNICATION port for settings as well as monitoring and control of the circuit breaker they protect from a remote station. The port shall also be available to allow local setting of the relay through PC-based software for the purpose of setting the relays and the software shall not be of proprietary software. The software and all documentation shall be provided in this Contract. The relays shall accept IRIG-B time code synchronization and include a battery backed time clock to retain date and time during de-energization. Cases housing the protection and control modules shall be made of noncorrosive materials such as aluminium. The design of the case and modules shall be such that it shall have high immunity against electrical disturbances according to IEC 60255 and electromagnetic compatibility (EMC) compliance. The generator protection relays shall come with voltage inputs to provide the
following protection elements: –
(a) over/under-voltage;
(b) over/under-frequency;
(c) under-power;
(d) reactive power; and
(e) power factor.

 

The generator protection relays shall also include the following minimumfunctions: –
(a) Over-speed (12);
(b) Over-excitation detection based on volts/hertz measurement. One definite-time and a composite definite/inverse-time element shall be provided (24);
(c) Under-voltage (27);
(d) Inadvertent generator energization (50/27);

(e) Sensitive directional power elements with flexibility to provide anti-motoring, over-power, or low-forward power indication (32);
(f) Loss of field (40Q);
(g) Negative-sequence over-current elements, including definite time and inverse-time operating characteristic (46);
(h) Voltage phase reversal (47);
(i) Instantaneous overcurrent (during start-up) (50S);
(j) Phase, residual, and neutral instantaneous, definite-time, and inverse-time non-directional over-current elements (50/51GN);
(k) Voltage restrained phase over-current (51V);
(l) Phase, positive-sequence, negative-sequence, and residual overvoltage elements (59); and
(m) Over and under-frequency (81).
Notwithstanding the functions provided as described above, the generator protection relays shall also provide all electrical protection relays as described in Section

13.1 – Electrical Protection Relays and Instrumentations.
The generator protection relays shall include metering and monitoring functions to indicate the following:-
(a) Measured current and voltage magnitudes and phase angles. Third-harmonic neutral and terminal voltage magnitudes. Volts/Hertz, percent of nominal;
(b) Single- and three-phase real and reactive power (KW, KVAR) and power factor (PF);
(c) Single- and three-phase real and reactive directional energy (KWh, KVARh);
(d) System frequency;

(e) Maximum and minimum log for Ia, Ib, Ic, In, Va, Vb, Vc, Vn, 3∅ KW, and KVAR; and
(f) DC battery voltage monitoring and metering. In addition, the generator protection relays shall retain in non-volatile memory, the following:
(a) A sequence of events record consisting of the latest time-tagged events; and
(b) No fewer than 15 latest event reports containing voltage and current measurements, contact input and output status, and relay element conditions. Record formats displaying 4 and 16 samples per cycle shall be available.

 


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