Points to be Taken Care While preparing SLD's

POINTS TO BE TAKEN CARE WHILE PREPARING MASTER SLD’S:

SLD (Single Line Diagram) is the simplified representation of the Circuits or connections of the electrical network. Simple Symbols and lines are used to draw the Single line Diagram.

SLD - Image

1. Keep and refer the BOQ & the Specifications before starting SLD preparation

2. Prepare and keep the various calculations like voltage drop, short circuit and earthing.

3. Collect all the inputs required for the SLD like Lighting, Power, HVAC, Plumbing and Fire

     Fighting System loads

4. List down all the major equipment's involved in the project as below:

• RMU Metering Panel
• Consumer HT Panel( If applicable)
• Substation HT Panel
• Transformers
• NGR (If applicable)
• DG Set
• Bus duct
• UPS
• Inverter
• Rising Mains
• Rising Mains End Feed Unit
• Auto. Synchronizing Panel/AMF Panel
• Main LT Panel
• APFC Panel
• Lighting Sub-Panel
• Power Sub-Panel
• UPS Sub-Panel
• Emergency Panel
• Fire MCC Panel
• Pump MCC Panel
• HVAC MCC Panel
• AHU Distribution Panel
• AHU Local Control Panel
• VFD Panel
• Ventilation Panel
• RTCC Panel
• External Lighting Panel
• Lift Panel

5. Check & indicate the incoming supply source with voltage class

6. Check whether isolator (or) VCB (or) SF6 is used in the metering panel & indicate accordingly

7. Check and incorporate the type of CT’s (Metering & Protection), CT ratios, Class of CT’s &

     VA of CT’s.

8. Check and incorporate the type of PT’s, Class of PT, PT ratios, VA of PT’s

9. Check the type of metering being provided (ETVM/EEM metering) & indicate accordingly

10. Check & incorporate the type of relays being proposed for the project from the master list of

      relays as mentioned as below:

• Instantaneous Over current Relay – Required for Transformer feeders
• IDMT Over current Relay – Required for all circuit breakers
• Instantaneous Earth fault Relay – Required for Transformer feeders
• IDMT Earth fault Relay – Required for all circuit breakers
• Restricted Earth fault Relay – For Transformers more than or equal to 2000KVA
• Differential Protection Relay – For Transformers more than or equal to 10MVA
• Lockout Relay(Master Relay) – For all circuit breakers
• DC Healthy Relay, Trip Circuit supervision Relay, Alarm/Auxiliary Relay, Under, Voltage Relay - For all Circuit Breakers

11. Check & indicate the auxiliary items like indication lamps, Annunciation panel, Operation

      counter, Ammeter, Voltmeter, etc.,

12. Check & indicate the Short circuit ratings of all Bus Bars, Circuit Breakers and Cables.

13. Check & indicate the type (Dry/Oil), Outdoor/Indoor, rating, Voltage transformation Ratio,

      OLTC/off circuit tap changing ratio, type of connection, of Transformers

14. Check whether NGR to be provided for Transformer / DG (or) not & indicate the same

15. Indicate the size, type of core, no. of runs, length for all the cables

16. Indicate the Connected Load, Maximum Demand, Name & Location in all the panels

17. Check & Indicate the bus duct with ratings (Bus ducts required for Transformer/DG with

      capacity more than or equal to 750KVA)

18. Check whether sandwich bus duct (or) air insulated Bus duct is proposed & indicate

      accordingly

19. Check whether Auto. Synchronization Panel (or) AMF panel is proposed and indicate

      accordingly

20. Check the interlocking in the HT/LT panel & indicate the interlocking logic separately

21. Check whether ACB’s/MCB’s are with microprocessor based release (or) not and indicate the

      same in note accordingly.

22. Check whether ACB’s are MDO or EDO type & indicate accordingly

23. Check for meter (EEM/ETVM) in all panels & indicate accordingly

24. Check the I/O summary and indicate in notes, The provisions to be made for BMS in various

      panels/equipment's

25. Indicate all the legends in the SLD

26. Indicate all relevant notes covered for the SLD

27. Indicate all reference drawings to this SLD

28. Check the title block for the following:

• Drawing released as GFC/Preliminary/Tender/Information/Approval
• Title of the drawing
• Dates
• Revision History

NOTE:

• Ratings of all the equipment's should be well marked clearly so that the amp ratings should not differ from each other for the same load.
• All the relevant relay codes should be covered while implementing the protection devices in the SLD
• Standard naming is to be followed for all the devices and equipment's while preparing the SLD
• Every feeder should have it’s connected load marked on it
• Panels should be placed legibly and reduce congestion with all the necessary details and all theabove mentioned data.
• MCB, ACB, VCB should be segregated according to the load current
• Cross check whether the total load indicated in the main LT panel is the sum of all the loads being fed from the panel.