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MV cubicles shall be metal clad type with 1 feeder inlet (depend on the National Electric Company’s approval), sectioning, transformer outlets and measuring systems. 

Medium voltage cubicle structure will have following type. Transformation ratios and classifications for current/voltage transformer will be confirmed by Local Electricity Supplier. 

If CHP (if any) unit is connected to HV line, the Contractor shall provide additional switchgear for CHP unit. HV switchgear unit shall be communicated with SCADA system via Ethernet for energy consumption. 

There will be power analyzer / protection relay with Ethernet/bus Communication in medium voltage cubicles. It will communicate with SCADA system via Ethernet. 

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Power circuit breakers and disconnectors shall be three-pole types, and metal-clad draw out SF6 GAS / Vacuum circuit breaker system. Circuit breakers shall be foreseen for inlet and transformer outlets. Protection relay shall be considered for each MV cubicle with circuit breaker. 

Load disconnectors shall have characteristics commensurate with the circuit they supply and a load break capacity in excess of the total load of the circuit they supply. 

Power circuit breakers rated switching capacity shall be at least equal to the total load of the circuit they supply. Power circuit breakers shall be provided with adjustable instantaneous short circuit and overload trips relays to allow for changes in the site load, and to allow for plant expansion. The prospective fault level must not be higher than the breaker capacity, and the time/current tripping characteristics shall be chosen and set with due regard to the equipment performance and circuit data, and to assure discrimination between series connected power circuit breakers. The power circuit breaker closest to a fault shall clear the fault. If it fails the upstream power circuit breaker shall clear the fault. 

Power circuit breakers shall be fitted with a protection system to comprise the following facilities: 

 Single phase failure trip 

 Earth fault trip 

 Thermal overload trip 

 Short circuit trip 

The power circuit breakers shall comply with IEC 60265 and 60420. 

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All power circuit breakers shall be automatically controlled from the protection equipment (gas alarm, high temperature alarm, overcurrent, short circuit and I$^{2}$t thermo). 

