SLD for the written switching procedure
Black colour is what I wrote
Red colour is the correction or further explanation.
Job Sheet: To perform maintenance at Ring Main Unit (2 + 1) at Pencawang Elektrik Kg Jelutong
(RMU 2+1 means 2 feeder and 1 Tx)
Preparation at all substations
1. Wear complete arc flash PPE
2. Note any alarms, trips and conditions of switch gears
3. Ensure rubber mat is available at all time
4. Ensure that HT voltage stick and multimeter are in good working condition.
• the steps above are done at each substation prior to commencing of switching work,
P/E Kg Jelutong
1. Inform OIC
2. At FA NOP
2. Note any alarms, trips and conditions of switch gears
3. Ensure rubber mat is available at all time
4. Ensure that HT voltage stick and multimeter are in good working condition.
• the steps above are done at each substation prior to commencing of switching work,
P/E Kg Jelutong
1. Inform OIC
2. At FA NOP
A. Perform voltage measurement at bus bar
a. Must state I.e. measured voltage is at 230VAC ph-n and 400VAC ph-ph within 10%, -6% tolerance for both bus bar and cable
B. Perform voltage measurement at cable
C. Perform phase rotation check at bus bar
a. Clockwise rotation for both bus bar and cable
D. Perform phase rotation check at cable
E. Perform phasing check between bus bar and cable
a. 0 VAC for in phase and 400VAC for out of phase
3. Off 3008 CNx2, NSLx2 (CN NSL at each isolator and E/S)
a. Must state I.e. measured voltage is at 230VAC ph-n and 400VAC ph-ph within 10%, -6% tolerance for both bus bar and cable
B. Perform voltage measurement at cable
C. Perform phase rotation check at bus bar
a. Clockwise rotation for both bus bar and cable
D. Perform phase rotation check at cable
E. Perform phasing check between bus bar and cable
a. 0 VAC for in phase and 400VAC for out of phase
3. Off 3008 CNx2, NSLx2 (CN NSL at each isolator and E/S)
4. PCD 3008 through voltage indicator
5. CME 3008 CN NSL (at E/S)
6. PCD at L1
7. Remove Link + Neutral at L1
8. Remove F1 CN NSL
9. CME L1 cable to Transformer
5. CME 3008 CN NSL (at E/S)
6. PCD at L1
7. Remove Link + Neutral at L1
8. Remove F1 CN NSL
9. CME L1 cable to Transformer
10. Insert FA fuse
A. Check shorting and fuse feedback
B. SL removed
11. Bus bar
A. Perform phase rotation check and voltage measurement
12. Insert F1 fuse
A. Check shorting and fuse feedback
13. Open 3007 CNx2, NSLx2
14. Open 3009 CNx2, NSLx2
15. Inform OIC
PE Malim Nawar
A. Perform phase rotation check and voltage measurement
12. Insert F1 fuse
A. Check shorting and fuse feedback
13. Open 3007 CNx2, NSLx2
14. Open 3009 CNx2, NSLx2
15. Inform OIC
PE Malim Nawar
1. Inform OIC
2. Open 3006 CNx2 NSLx2
3. PCD 3006 via voltage indicator
4. CME 3006 CN NSL
5. Inform OIC
PE Tg Bangkong
1. Inform OIC
2. 1006 already Open (NOP)
3. Rack out 1006 DN CNx3 SL -> NSLx4
A. DN NSL bus bar shutter
B. CN NSL at each Cable shutter, E/S and VCB door
4. Check HT voltage stick healthiness
5. PCD at 1006 cable spout
A. Open door, open cable spout shutter
B. CN NSL back after PCD
6. Check HT voltage stick healthiness
7. CME 1006 CN x 2 NSLx2 (door and E/S)
8. Inform OIC
PE Kg Jelutong
2. Open 3006 CNx2 NSLx2
3. PCD 3006 via voltage indicator
4. CME 3006 CN NSL
5. Inform OIC
PE Tg Bangkong
1. Inform OIC
2. 1006 already Open (NOP)
3. Rack out 1006 DN CNx3 SL -> NSLx4
A. DN NSL bus bar shutter
B. CN NSL at each Cable shutter, E/S and VCB door
4. Check HT voltage stick healthiness
5. PCD at 1006 cable spout
A. Open door, open cable spout shutter
B. CN NSL back after PCD
6. Check HT voltage stick healthiness
7. CME 1006 CN x 2 NSLx2 (door and E/S)
8. Inform OIC
PE Kg Jelutong
1. Inform OIC
2. Ensure that 3007, 3008 and 3009 are already Open.
3. PCD 3007
A. This is where the mistake started
B. Assumed to discharge bus bar through 3007 switch and 1006 Earth since the cable is already earthed at 1006, but cable is possibly long and there could be a voltage build up from induction etc at 3007 cable end.
C. Did exercises and attended ILSAS training and did it right. Read similar switching steps the night before, did some mock switching steps a few days earlier. Somehow during that given 35-40 minutes, I wrote it differently.
D. Correct steps in no. 10
4. Close 3007 to discharge bus bar
5. Open 3007 CNx2 NSLx2
6. PCD 3007
7. CME 3007 CN NSL
8. PCD 3009
9. CME 3009 CN NSL
2. Ensure that 3007, 3008 and 3009 are already Open.
3. PCD 3007
A. This is where the mistake started
B. Assumed to discharge bus bar through 3007 switch and 1006 Earth since the cable is already earthed at 1006, but cable is possibly long and there could be a voltage build up from induction etc at 3007 cable end.
C. Did exercises and attended ILSAS training and did it right. Read similar switching steps the night before, did some mock switching steps a few days earlier. Somehow during that given 35-40 minutes, I wrote it differently.
D. Correct steps in no. 10
4. Close 3007 to discharge bus bar
5. Open 3007 CNx2 NSLx2
6. PCD 3007
7. CME 3007 CN NSL
8. PCD 3009
9. CME 3009 CN NSL
10. Steps 3 to 9 should be like this...
A. PCD 3007
B. CME 3007 CN NSL
Always remember CME cable both sides 3007 and 1006
C. PCD 3009
D. CME 3009 CN NSL
Always remember CME cable both sides 3009 and 3006
E. Open CME 3007 CN NSL
F. Close 3007 for 10 seconds
G. Open 3007 CNx2 NSLx2
H. PCD 3007
I. CME 3007 CN NSL
11. Request OIC authorisation
12. Issue PTW
Then after, it was kind of fast after the switching procedure explanation. Some questions that I remember:
A. PCD 3007
B. CME 3007 CN NSL
Always remember CME cable both sides 3007 and 1006
C. PCD 3009
D. CME 3009 CN NSL
Always remember CME cable both sides 3009 and 3006
E. Open CME 3007 CN NSL
F. Close 3007 for 10 seconds
G. Open 3007 CNx2 NSLx2
H. PCD 3007
I. CME 3007 CN NSL
11. Request OIC authorisation
12. Issue PTW
Then after, it was kind of fast after the switching procedure explanation. Some questions that I remember:
1. Can the competent person (CP) issuing the authorisation become the receiving party for PTW if the repair work was done internally and there are no other CP?
2. What is the difference of phase rotation check and phasing check?
3. What are the jobs of a competent person? From another candidate.
4. Initially, I was not sure how detail each step should be explained but after some time only I understood assessor’s explanation I.e. when doing work at 1006,
a. They wanted to know where exactly DN CN NSL were applied,
b. How was the transition for PCD, I.e. in detail, told them HV stick proof check, open door and open cable shutter, PCD, then Apply back CN NSL at cable shutter and door respectively. The HV Stick prove check again.
c. So make sure, you tell as detail as you can. They may be suspecting that you are memorising the steps instead of really knowing it
I'm okay with whatever the outcome of the interview. Result should be out in the system soon. Hoping for the best.
Hope the above will help the first timers to ace the interview.
Abbreviations
CME - Circuit Main Earth
CN - Change Notice
CP - Competent Person
DN - Danger Notice
E/S or ES - Earthing Switch
HV - High Voltage
NOP - Normal Off Point
NSL - Non Standard Lock
OIC - Officer in Charge at RCC
PCD - Prove Circuit Dead
PE - Pencawang Elektrik
PMU - Pencawang Masuk Utama
PPK - Pencawang Pembahagian Kecil
PPU - Pencawang Pembahagian Utama
PTW - Permit To Work
RCC - Regional Control Centre
RMU - Ring Main Unit
SL - Standard Lock
3. What are the jobs of a competent person? From another candidate.
4. Initially, I was not sure how detail each step should be explained but after some time only I understood assessor’s explanation I.e. when doing work at 1006,
a. They wanted to know where exactly DN CN NSL were applied,
b. How was the transition for PCD, I.e. in detail, told them HV stick proof check, open door and open cable shutter, PCD, then Apply back CN NSL at cable shutter and door respectively. The HV Stick prove check again.
c. So make sure, you tell as detail as you can. They may be suspecting that you are memorising the steps instead of really knowing it
I'm okay with whatever the outcome of the interview. Result should be out in the system soon. Hoping for the best.
Hope the above will help the first timers to ace the interview.
Abbreviations
CME - Circuit Main Earth
CN - Change Notice
CP - Competent Person
DN - Danger Notice
E/S or ES - Earthing Switch
HV - High Voltage
NOP - Normal Off Point
NSL - Non Standard Lock
OIC - Officer in Charge at RCC
PCD - Prove Circuit Dead
PE - Pencawang Elektrik
PMU - Pencawang Masuk Utama
PPK - Pencawang Pembahagian Kecil
PPU - Pencawang Pembahagian Utama
PTW - Permit To Work
RCC - Regional Control Centre
RMU - Ring Main Unit
SL - Standard Lock
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