1. Metal-Clad SwitchgearMetal-Clad Switchgear
Installation & Precommissioning InspectionInstallation & Precommissioning Inspection
April 15, 2007
Abdullah M Al-Dushaishi

2. 2
OUTLINEOUTLINE
EQUIPMENT INSTALLATION INSPECTION
BUSBAR INSTALLATION INSPECTION
CABLE CONNECTION INSPECTION
GROUNDING CONNECTION INSPECTION
SOME DESIGN CONCERNS
PRE-COMMISSIONING
REFERENCES

3. 3
EQUIPMENTINSTALLATIONEQUIPMENTINSTALLATION
INSPECTIONINSPECTION
Ensure that adequate protection is provided when installing
switchgear
Switchgear shall only be installed in an indoor, air-conditioned
environment
Switchgear shall have an unobstructed horizontal space of:
a) Not less than 2 meters in front
b) Not less than 1 meter in back and sides
Spacing requirement between equipment shall be based upon
the largest dimension for either

4. 4
EQUIPMENTINSTALLATIONEQUIPMENTINSTALLATION
INSPECTIONINSPECTION
Lifting/handling devices shall be provided within a room
containing switchgear to mechanically assist in removing to
floor level, any withdrawable component (e.g., circuit breaker,
contactor, potential transformer, etc.) weighing over 20 kg
Switchgear shall be free of any physical damage after
installation
Switchgear should be properly anchored to its foundation

5. 5
EQUIPMENTINSTALLATIONEQUIPMENTINSTALLATION
INSPECTIONINSPECTION
Switches, circuit breakers, and other operating mechanisms
shall be manually exercised to make sure that they are
properly aligned and operate freely
Grounding connections shall be made properly
Debris, scrap wires and surplus shall be removed from the
switchgear interior before closing the enclosure

6. 6
EQUIPMENTINSTALLATIONEQUIPMENTINSTALLATION
INSPECTIONINSPECTION
Covers, doors & enclosure parts shall
be properly tightened
The switchgear shall be vertically &
horizontally aligned before anchoring
Check components for proper
identification as per IFC drawings and
specifications
Nameplate on equipment shall conform
to single line diagrams and schematics

7. 7
EQUIPMENTINSTALLATIONEQUIPMENTINSTALLATION
INSPECTIONINSPECTION
Concrete floor in front of switchgear shall be flush with the
roller level of lower breaker carriage rack and have a smooth
surface to facilitate removal and rolling of breaker
The bay spacing of transformers and the location of the
incoming circuit breakers on switchgear lineups shall be
positioned to minimize metal enclosed bus or cable bus length
and/or eliminate bends
Preferably, incomer circuit breakers shall be located at ends
of switchgear lineup
Unavoidable bends in cable bus or metal enclosed bus shall
be inside the substation building

8. 8
BUSBAR INSTALLATIONBUSBAR INSTALLATION
INSPECTIONINSPECTION
Neutral buses shall not be used within
switchgear
Cable shall not be used to extend the
main bus of switchgear

9. 9
BUSBAR INSTALLATIONBUSBAR INSTALLATION
INSPECTIONINSPECTION
Contact surfaces for the main bus
connections shall be clean
Tightness of bolted bus joints are correct
as per manufacturer's instruction for the
proper torque (foot-pound) levels

10. 10
CABLECONNECTION INSPECTIONCABLECONNECTION INSPECTION
Cable phasing shall be in accordance
with connection diagram
Proper cable tags shall be provided
Cables termination shall be in accordance
with cable manufacturer's instruction
Cable connections are clean and securely
bolted.
Bolt torque values shall be as per
manufacturer's specifications

11. 11
GROUNDING CONNECTIONGROUNDING CONNECTION
INSPECTIONINSPECTION
Sections of ground bus previously disconnected at shipping
sections shall be reconnected when units are installed
Secondary wirings are connected to switchgear ground bus as
indicated on IFC drawings
Ground bus shall be connected direct to grounding grid and
shall not run in metal conduit unless conduit is adequately
bonded to the circuit

12. 12
SOMEDESIGN CONCERNSSOMEDESIGN CONCERNS
Switchgear shall not be used to control:
low voltage motors and
high voltage motors rated less than 5kV
In industrial facilities, 480V switchgear shall not be fed from
4160V systems
A separate 120 VAC branch circuit shall be provided for the
space heater

13. 13
PRE-COMMISSIONINGPRE-COMMISSIONING
Check electrical relays, meters, or
instruments to determine connections
are made properly and devices function
properly
Check settings of the adjustable
current and voltage trip mechanisms to
confirm that they are at proper values.
Check control, power transformer and
PT fuses for size, type, and circuit
location
Check PT and CT ratios

14. 14
PRE-COMMISSIONINGPRE-COMMISSIONING
Check wiring connections for
tightness at instrument transformers
and terminal blocks
Protective devices’ setting for
current, voltage, or other relays shall
be done on-site in accordance with
manufacturer’s recommendation
Ground-fault protection system shall
be tested in accordance with
manufacturer's instruction

15. 15
PRE-COMMISSIONINGPRE-COMMISSIONING
Protective relays, overcurrent trip devices, and breakers shall
be tested for correct connections and operation at factory
Factory test results shall be referenced during
Precommissioning

16. 16
PRE-COMMISSIONINGPRE-COMMISSIONING
Insulation resistance test shall be performed to make sure
switchgear is free from short circuits and grounds. This test shall
be done both phase to ground and phase to phase and with the
switches and breakers both opened and closed
Switchgear busbar shall be tested for insulation resistance with
a 1-minute test (phase to phase and phase to ground) with 1kV
megohmmeter
Instrument transformers shall be tested for insulation resistance
with a 1-minute test with 1 kV megohmmeter

17. 17
PRE-COMMISSIONINGPRE-COMMISSIONING
Each circuit breaker protective relay device shall be calibrated
and tested with final settings in accordance with relay setting
summary or coordination study
With CT disconnected, CT secondary circuit shall be tested for
continuity and operation of applicable relays and meters by
applying current to the CT secondary winding
PT secondary circuit shall be tested by applying voltage to the
PT secondary, with PT disconnected, verifying operation of all
applicable relays and meters

18. 18
PRE-COMMISSIONINGPRE-COMMISSIONING
Space heaters, switching and indicating devices shall be tested
for operation
Auxiliary devices interlocks shall be tested for operation
Local and remote control devices/circuits shall be tested
according to engineering specification

19. 19
REFERENCESREFERENCES
NFPA 70 --National Electrical Code, 2005
NETA ATS -- Acceptance Testing Specification for Electrical
Power Distribution Equipment and Systems, 1999
SAES-P-116 -- Switchgear and Control Equipment, 28
February 2005
SAES-P-119 -- Onshore Substations, 30 march 2005