GE Industrial Solutions AKD-20 Low Voltage Switchgear - Manuel (Page 59)

AKD-20 Low Voltage Switchgear
Chapter 9. Maintaining the Switchgear
59 ©2012 General Electric All Rights Reserved
Lubrication
In general, the circuit breaker requires moderate lubrication.
Bearing points and sliding surfaces should be lubricated at the
regular inspection periods with a thin film of GE lubricant
D6A15A2. Before lubricating, remove any hardened grease and
dirt from latch and bearing surfaces with mineral spirits then
wipe with a clean rag.
CAUTION: All excess lubricant should be removed with a
clean cloth to avoid accumulation of dirt or dust.
ATTENTION: Il faut enlever complètement tout excès de
lubrifiant avec un linge propre afin d’éviter l’accumulation de
saletés ou de poussières.
On drawout breakers, the contact surface of the disconnect
fingers should be cleaned and greased with GE lubricant
D6A15A2.
Instruments, Instrument Transformers, and
Relays
Check and inspect all devices to see that they are functioning
properly. Check that all electrical connections are tight. Check
mounting of the device.
Under normal conditions, the protective relays do not operate;
therefore, it is important to check the operation of these devices
regularly. Refer to Relay Instruction Books for detailed
instructions.
Breaker Compartment Interiors
WARNING: De-energize equipment completely before doing
maintenance work in compartments. This includes de-
energizing any connections to outside primary or secondary
sources, such as transformers, tie lines, etc.
ADVERTISSEMENT: Mettre l’équipement complètement hors
tension avant d’entreprendre tout travail de maintenance sur
tout dispositif, raccordement, barres omnibus ou les
compartiments des câbles d’alimentation. Cela inclut la mise
hors tension des raccordements aux sources primaires et
secondaires tels que les transformateurs et les
interconnexions.
1. Thoroughly clean the interior of the breaker and
instrument compartments. Use a vacuum cleaner and
clean rags only. Do not use steel wool or oxide papers.
Blowing with compressed air is not recommended.
2. Check indicating devices, mechanical and key interlocks.
3. Check primary disconnecting device contacts for signs of
abnormal wear or overheating. Discoloration of the
silvered surfaces is not ordinarily harmful. These contacts
should be cleaned only by wiping with a lint-free cloth.
4. Clean the racking mechanism and lubricate with GE
lubricant D6A15A2.
5. Before replacing the breaker, wipe off the primary
disconnecting device contacts. Apply a thin coat of GE
lubricant D6A15A2 to the stationary studs and to the
primary disconnects on the breaker.
9-3 Bus Area
WARNING: De-energize equipment completely before doing
maintenance work on any devices, connections, bus work,
breaker or feeder cable compartments. This includes de-
energizing any connections to outside primary or secondary
sources, such as transformers, tie lines, etc.
ADVERTISSEMENT: Désamorcer complètement l’équipement
avant d’effectuer du travail de maintenance dans les
compartiments. Cela inclut le désamorçage de toute
connexion aux sources primaires et secondaires, telles que
les transformateurs et les interconnexions.
Inspect and check the bus area as follows:
1. Inspect the buses and connections carefully for evidence
of overheating or weakening of the insulating supports. If
bus insulation is present, remove the molded covers over
the main bus connection to expose joints for inspection.
2. Check all connection bolts in the bus compartment and all
bracing bolts for tightness. See the Torque Table A-1 in
Appendix A.
3. Vacuum and, with a clean rag, wipe the buses and
supports.
4. Visually inspect the insulation on the bars that run from
the breaker studs through the bus structure to the cable
area.
5. After cleaning, megger and record the resistance to
ground and between phases of all insulated bars and all
buses and connections. Disconnect all control circuits
before checking resistance. Do not use over a 1500-volt
megger. Since definite limits cannot be given for satis-
factory insulation resistance values, a record must be kept
of the readings.
Weakening of the insulation from one maintenance period to the
next can be recognized from the recorded readings. The
readings should be taken under similar conditions each time, if
possible, and the record should include the ambient
temperature and humidity.
9-4 Cable and Busway Compartment
Inspect and check the cable and busway compartment as
follows:
1. Inspect all power cable connections for signs of
overheating and tighten all connections. If severe
discoloration or if damage is apparent, remove the
damaged portion of the cable.
CAUTION: Be sure the condition which caused the over-
heating has been corrected before energizing.
ATTENTION: Assurez-vous que la condition ayant causé le
surchauffement a été corrigée avant de mettre sous tension.