Direct 11kV Supply for High - Rise Towers above 200m / Industrial / Private Load

11.9 Direct 11kV Supply for High - Rise Towers above 200m / Industrial / Private Load

1. 
   Intake arrangement and protection requirements
   

1. 
   Point of supply is the supply intake of MV switchgear for the project which is located adjacent to DEWA metering/control room.
   
2. 
   Beyond point of supply all the equipment (like switchgear, transformer, cable etc.,) has to be procured, installed, commissioned, operated and maintained by the owner of the project.
   
3. 
   DEWA will not supply, operate or maintain any equipment to be installed above ground level.
   
4. 
   All equipment (Circuit Breaker, Transformer etc.) procured by party shall have dual ratio (6.6/11/22KV) unless clearly advised by that it is 11/22 KV.
   
5. 
   All equipment shall be compliant with international standards (IEC standards).
   

6. 
   Comply with the planning levels of voltage flicker based on IEC 61000-3-7: ed 2.0-2008. Accordingly, voltage dip calculations shall be submitted along with the motor specification, starting characteristics, number of motor starts per day, SLD drawings etc. for approval at design stage.
   
7. 
   For loads that injects harmonics currents into network, harmonic study shall be prepared and approved at the design stage, to comply with the planning limits of Harmonic Emissions for voltage and current based on IEC 61000-3-6: ed2.0-2008 and IEC 61000– 3-12: ed2.0-2011 respectively.
   
8. 
   Harmonics and Flickers measurements shall be conducted after commissioning of project and report of measurements shall be submitted.
   
9. 
   Total losses of transformer shall not exceed 1.5% of rated capacity due to conservation reasons.
   
10. 
    Power factor at point of supply shall be maintained at 0.95 or higher.
    

11. 
    Incomer of the project shall be switchgear with circuit breaker, with E/F & O/C protection and shall be located adjacent to a DEWA meter/ Control room.
    

12. 
    LV distribution shall comply with authority guidelines and standards.
    

13. 
    Cast Resin transformers (fire resistant transformers) shall be allowed to install in residential / commercial buildings.
    
14. 
    Technical Justification shall be submitted for availing direct 6.6/11/22 KV supply to the high-rise building for locating transformers above ground level/s. This depends on the height of the building, size of load, type of load, etc. Normally, buildings of height 200m or above shall be considered for direct 6.6/11/22 KV supply.
    
15. 
    MV Switchgear shall be suitable for termination of 3x240 mm² XLPE/PVC/SWA/PE Aluminum/ Cu Cable with heat shrinkable type cable terminations.
    
16. 
    Termination at the private MV switchgear incomer shall be done by the consumer and terminations at DEWA RMU shall be done by DEWA.
    
17. 
    Suitable protection and interlocking shall be provided to ensure that a private substation shall not have any negative impact on the DEWA system.
    
18. 
    There shall be sufficient discrimination between DEWA protection and that of the private substation so that the protection at private substation operates earlier to the DEWA protection during fault.
    
19. 
    Mechanical and electrical interlocks shall be provided so that the incomers shall not be paralleled. In substations with multiple switchboards, the interlock shall be extended to all the switchboards.
    
20. 
    The drawings shall use ANSI standard codes for depicting protection relay functions as well as contain a legend.
    
21. 
    The incomer protection relays shall comply with IEC 60255 and shall be supported by type test and guaranteed routine manufacture’s works test certificates. Only certificates confirming that the relay has passed the type tests needs to be submitted to DEWA.
    
22. 
    The over current relay shall operate correctly for fault currents up to 25 kA.
    

23. 
    The instrument transformers shall comply with IEC 61869 and be supported by type test certificates and guaranteed routine manufacture’s works test certificates. Only certificates confirming that the current transformers have passed the type tests needs to be submitted to DEWA.
    
24. 
    The incomer current transformer shall be dimensioned so that the protection scheme will operate effectively for a fault current of 25 kA.
    
25. 
    Reverse power protection shall be provided to ensure that in-feeds to faults within the DEWA 11-22 kV network are cleared within 3 seconds.