Alberta Electric System Operator
System Co-ordination Plan
2026-05-14 to 2026-05-22
Approved Outages

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From To Owner Type Element Scheduled Activity Date/Time Comments Interconnection
26-Jul-24 10:00 31-Jul-26 16:00 ATCO Outage 826s 504R (826s Marguerite Lake) emergency removal to replace failed 502R @834S 735.25 Days
Continuous		  
23-Aug-24 13:45 21-May-26 14:29 ALTALINK Outage 157s C1 (157s Lac La Biche) forced outage 636.03 Days
Continuous		  
20-Mar-25 08:00 29-May-26 17:00 ALTALINK Outage 256s C1 (256s Harmattan) forced outage 435.38 Days
Continuous		  
12-Sep-25 08:00 14-May-26 16:00 ENMAX Outage 33.1TR (SS-33) tap changer refurbishments. soak test required 244.33 Days
Continuous		  
25-Nov-25 17:46 18-Sep-26 18:00 ATCO Outage 876s 901T (876s Brintnell) forced outage oil leaking 296.97 Days
Continuous		  
27-Nov-25 08:30 27-Nov-27 16:30 ALTALINK TE 89s Protection & Control (89s Ellerslie) DSP card replacements on1057L B87/L3 and B240B1 B87/240B1 730.33 Days
Daily		  
04-Jan-26 08:00 02-Sep-26 16:00 SUNCOR Outage 29EDD-34 260kV Bus 29PP-45 (29EDD-34), 29EDD-34 29-952-113 (29EDD-34), 29EDD-34 29PS-216 (29EDD-34) urgent repairs on 29PT-224 at 29EDD34 on 29PP-45 bus 241.29 Days
Continuous		  
12-Jan-26 07:00 03-Jul-26 17:00 EPCOR TE 330p Protection & Control (330p Genesee) protect blocking, annual relay maintenance and password changes 172.38 Days
Continuous		  
21-Jan-26 08:00 30-Oct-26 16:00 ENMAX Outage 5.7TR (SS-5) 25kV switchgear replacement 282.29 Days
Continuous		  
03-Feb-26 09:00 09-Jul-26 17:00 ATCO TE 972s RTU/SCADA (972s Tinchebray) config changes needed throughout the CETO project 156.29 Days
Continuous		  
09-Feb-26 09:00 09-Jul-26 17:00 ATCO TE 972s Protection & Control (972s Tinchebray) block all 50BF protection until cutovers and associated commissioning are complete 150.29 Days
Continuous		  
06-Mar-26 17:00 13-Nov-26 17:00 EPCOR Outage T1 (Woodcroft) woodcroft: TX1 LCR civil 252 Days
Continuous		  
10-Mar-26 10:00 30-Nov-26 17:00 ATCO TE 743s RTU/SCADA (743s Sarah Lake) throughout the course of the project, different apparatus are being replaced, RTU will be blocked prior to download 265.33 Days
Continuous		  
11-Mar-26 13:45 15-May-26 16:00 ALTALINK Outage 535s C1 (535s Joffre) breaker maintenance 65.09 Days
Continuous		  
22-Mar-26 13:00 30-Jun-26 17:00 BHE Canada Outage 120s C1 (120s Picture Butte), 120s C2 (120s Picture Butte) forced outage 100.17 Days
Continuous		  
28-Mar-26 12:00 05-Jun-26 17:00 ATCO TE 833s RTU/SCADA (833s Mariana) updating RTU/station controller configuration during SCADA upgrade project 69.21 Days
Continuous		  
06-Apr-26 08:00 19-Jun-26 16:00 ALTALINK TE 37s RTU/SCADA (37s North Calder) RTU database updates 74.33 Days
Continuous		  
09-Apr-26 17:01 15-May-26 17:00 EPCOR Outage 72RW3 (Rossdale - Woodcroft), RW727 (Rossdale) termination rebuild at the Woodcroft end 36 Days
Continuous		  
13-Apr-26 07:00 29-May-26 17:00 EPCOR Outage 805s T4 (805s Jasper) bushing replacement and fan repair 46.42 Days
Continuous		  
13-Apr-26 09:00 21-May-26 10:00 ALTALINK Outage 157s C1 (157s Lac La Biche) replace breaker and disconnect switch 38.04 Days
Continuous		  
25-Apr-26 08:00 27-Jun-26 16:00 ENMAX Outage 1.82L (SS-1 - SS-5), 5B138-1.82 (SS-5) 1 sub Transmission line cut over 63.33 Days
Continuous		  
25-Apr-26 08:00 27-Jun-26 16:00 ENMAX Outage 1.84L (SS-1 - SS-5), 5B138-1.84 (SS-5) 1 sub Transmission line cut over 63.33 Days
Continuous		  
27-Apr-26 08:00 15-May-26 16:00 ALTALINK TE 37s Protection & Control (37s North Calder) P&C upgrades (37s4, 37s82, 37s88, 37s81) 18.33 Days
Continuous		  
27-Apr-26 08:00 28-May-26 08:00 Saskpower Outage Sask Power CC904T maintenance 31 Days
Continuous		 AB-SK
28-Apr-26 08:00 22-May-26 16:00 ENMAX TE Protection & Control (SS-32) 32 sub 138 kV autoswitching protection outage - HV switch replacement. MD-32.2TR, 32SW84, 32SW85, 32SW86, 32SW87, 32SW88 24.33 Days
Daily		  
28-Apr-26 08:30 22-May-26 14:00 ENMAX Outage 32.83L (SS-32 - SS-40), 26.81L (SS-26 - SS-32), 32.2TR (SS-32), 32.1TR (SS-32), 32B138-32BT5 (SS-32), 32B138-32.83 (SS-32), 32B138-26.81 (SS-32), 40B138-32.83 (SS-40), 26B138-26.81 (SS-26), 32MD138-32.1TR (SS-32), 32MD138-32.2TR (SS-32) HV SW replacement. MD-32.2TR, 32SW84, 32SW85, 32SW86, 32SW87, 32SW88 24.23 Days
Continuous		  
29-Apr-26 17:00 19-May-26 07:00 ALTALINK Outage 320p 2089 (320p Keephills) urgent customer work 19.58 Days
Continuous		  
01-May-26 17:00 25-Nov-26 17:00 EPCOR Outage T1 (Meadowlark) T1 LCR civil work 208.04 Days
Continuous		  
03-May-26 10:00 31-May-26 17:00 ATCO, ALTALINK Outage 9L960 (13s Deerland - 825s Whitefish Lake), 9L961 (13s Deerland - 825s Whitefish Lake) forced outage due to damaged structure
28.29 Days
Continuous		  
04-May-26 08:00 15-May-26 17:00 BCH, BPA Outage 2L112 (BPA Boundary - BCH Nelway) emergency replacement of a boundary PCB, BC maintenance does not affect the Alberta ATC 11.38 Days
Continuous		 AB-BC
04-May-26 08:00 22-May-26 16:00 ENMAX TE Protection & Control (SS-5) 5PT138-Z31 secondary voltage outage, SS-1 transmission line cut over 18.33 Days
Daily		  
04-May-26 08:00 22-May-26 16:00 ENMAX TE Protection & Control (SS-5) 1 sub transmission line cut over 18.33 Days
Daily		  
04-May-26 09:00 18-May-26 17:30 ATCO Outage 13L50 (2029s Heathfield - 2075s Newell) annual EATL outage at 2075s and 2029s 14.35 Days
Continuous		  
04-May-26 09:00 18-May-26 17:30 ATCO Outage 2029s T11 (2029s Heathfield), 2029s 1205 (2029s Heathfield), 2029s 1206 (2029s Heathfield) annual EATL outage 14.35 Days
Continuous		  
04-May-26 09:00 18-May-26 17:30 ATCO Outage 2075s T11 (2075s Newell), 2075s 916 (2075s Newell), 2075s 917 (2075s Newell) annual EATL outage 14.35 Days
Continuous		  
04-May-26 10:00 25-May-26 16:00 ATCO TE 825s Whitefish Lake RTU/SCADA isolations and modifications to alarm/ SCADA points, wiring, and configurations, may require shot duration 21.25 Days
Continuous		  
05-May-26 08:00 18-May-26 17:30 ATCO TE 2029s Protection & Control (2029s Heathfield) fire suppression inspection and recertification, install blocking switches, requires protection to be blocked, could case alarms to AML, valve cooling system maintenance and repairs. 13.4 Days
Continuous		  
05-May-26 08:00 18-May-26 17:30 ATCO TE 2075s Protection & Control (2075s Newell) fire suppression inspection and recertification, install blocking switches, requires protection to be blocked, could case alarms to AML, valve cooling system maintenance and repairs. 13.4 Days
Continuous		  
06-May-26 08:00 01-Jun-26 17:30 ATCO TE 743s Protection & Control (743s Sarah Lake) relay testing 50BF/700BS1 26.4 Days
Continuous		  
06-May-26 08:00 01-Jun-26 17:30 ATCO TE 743s Protection & Control (743s Sarah Lake) relay testing 87TA/701T 26.4 Days
Continuous		  
06-May-26 08:00 01-Jun-26 17:30 ATCO TE 743s Protection & Control (743s Sarah Lake) relay testing 51MV/701T 26.4 Days
Continuous		  
06-May-26 08:00 01-Jun-26 17:30 ATCO TE 743s Protection & Control (743s Sarah Lake) relay testing 51HV-51N/701T 26.4 Days
Continuous		  
07-May-26 09:00 19-May-26 17:00 ATCO Outage 972s 908 (972s Tinchebray), 972s 909 (972s Tinchebray) GOI is required on 907B to isolate 908/909 bay and new 9L16 12.33 Days
Continuous		  
07-May-26 14:00 14-May-26 17:00 ALTALINK, EPCOR Outage 37s Protection & Control (37s North Calder), 37s 88 (37s North Calder), 37s 82 (37s North Calder), 920L (37s North Calder - 557s Castle Downs), 37s 87 (37s North Calder) P&C upgrades (37s88, 37s82, PT21) 7.13 Days
Continuous		  
11-May-26 07:00 14-May-26 18:00 ATCO, ENBRIDGE, ALTALINK IO 7LA114 (658s Chard - 7L114 tap), 7L114 (72s Leismer - 7LA114 tap), 7L114 (907s Waddell - 7LA114 tap), 907s Waddell AltaLink outage on 72sT2 causing an outage to 7L114 at 907S 3.46 Days
Continuous		  
11-May-26 07:00 17-May-26 17:00 EPCOR Outage 814s T2 (814s Bellamy), BR722 (Rossdale), 814s B2402 (814s Bellamy), 814s B2406 (814s Bellamy), 814s BAB2 (814s Bellamy) TX2 zone doble, breaker maintenance/doble, and disconnect maintenance 6.42 Days
Continuous		  
11-May-26 07:00 22-May-26 17:00 EPCOR Outage 52s T1 (52s East Industrial), 52s E2401 (52s East Industrial) TX1 DGA monitor replacement 11.42 Days
Continuous		  
11-May-26 07:00 15-May-26 17:00 ALTALINK, EPCOR RB 711L (113s Inland Cement - 747L tap) 711L - aerial washing program 4.42 Days
Continuous		  
11-May-26 07:00 15-May-26 17:30 ALTALINK RB 747L (37s North Calder - 711L tap), 747L (99s North St. Albert - 711L tap), 711L tap 711L - aerial washing program 4.44 Days
Continuous		  
11-May-26 07:00 14-May-26 18:00 ALTALINK, ATCO Outage 72s T2 (72s Leismer), 72s 1052 (72s Leismer), 72s 2052 (72s Leismer), 72s 3052 (72s Leismer), 72s C1 (72s Leismer), 72s C2 (72s Leismer), 7L114 (72s Leismer - 7LA114 tap), 72s 31 (72s Leismer) T2 - maintenance, doble testing, Coresense and Qualitrol installation
72s1052 - 1st trip and breaker maintenance		 3.46 Days
Continuous		  
11-May-26 07:00 14-May-26 17:00 ALTALINK, ATCO IO 72s 1052 (72s Leismer), 7L114 (72s Leismer - 7LA114 tap) customer maintenance 3.42 Days
Continuous		  
11-May-26 08:00 14-May-26 16:00 ALTALINK TE 71s RTU/SCADA (71s Lamoureux), AltaLink Telecom Equipment upgrade firewall, MPLS nodes, MPLS raw socket 3.33 Days
Continuous		  
11-May-26 08:00 14-May-26 16:00 ATCO RB 7L75 (ATC 793s West Peace River - 800s Friedenstal) walk up and climbing inspection 3.33 Days
Continuous		  
11-May-26 08:00 14-May-26 16:00 ALTALINK Outage 74s 76 (74s Janet) 74s76 major maintenance 3.33 Days
Continuous		  
11-May-26 08:00 14-May-26 16:00 ALTALINK TE 127s RTU/SCADA (127s Bruderheim), AltaLink Telecom Equipment firewall upgrade, raw socket conversion, MPLS 7705A and 7705B upgrade 3.33 Days
Continuous		  
11-May-26 08:00 15-May-26 16:00 CMH TE MHS-7 Protection & Control (MHS-7 Brier Park) perform preventative maintenance on BPR-69-A 4.33 Days
Continuous		  
11-May-26 08:00 14-May-26 16:00 ENMAX Outage 16.1TR (SS-16) PT outage and transformer maintenance and testing 3.33 Days
Continuous		  
11-May-26 08:00 29-May-26 16:00 ALTALINK TE 1182s RTU/SCADA (1182s Berland River) RTU outage required for SCADA deficiency clean-up and SCN testing 18.33 Days
Continuous		  
11-May-26 08:00 15-May-26 16:00 ENMAX Outage 8.5TR (SS-8) transformer maintenance and testing 4.33 Days
Continuous		  
11-May-26 09:00 15-May-26 16:00 ATCO TE ATCO Telecom Equipment Codesa to Jean Cote EOL radio replacement - remove constellation radio and replace with IRU600
 4.29 Days
Continuous		  
11-May-26 13:00 14-May-26 09:00 ATCO Outage 2033s 703C (2033s Mowat) PRC trip coil testing and protection testing 2.83 Days
Continuous		  
11-May-26 13:30 14-May-26 17:00 ALTALINK Outage 38s 7452 (38s East Edmonton) 240kV breaker maintenance 3.15 Days
Continuous		  
11-May-26 18:00 08-Jun-26 08:00 ATCO, ALTALINK Outage 962L (87s Gaetz - 972s Tinchebray) switch needs to remain open until ATCO is ready @ 972s for energization 27.58 Days
Continuous		  
11-May-26 18:00 08-Jun-26 08:00 ATCO, ALTALINK Outage 986L (87s Gaetz - 972s Tinchebray) switch needs to remain open until ATCO is ready @ 972s for energization 27.58 Days
Continuous		  
12-May-26 07:00 19-May-26 17:30 ATCO TE 743s Protection & Control (743s Sarah Lake) relay isolation for 50BF/705 and 50BF/706 for settings update 7.44 Days
Continuous		  
12-May-26 08:00 14-May-26 16:00 ALTALINK TE 349s Protection & Control (349s Stavely) move relay to new City of Lethbridge communication system 2.33 Days
Continuous		  
12-May-26 08:00 14-May-26 17:00 Lethbridge TE 181s Protection & Control (181s Chinook) protection outages 2.38 Days
Continuous		  
12-May-26 08:00 25-May-26 16:00 Syncrude Outage 211 (Aurora), 213 (Aurora), 212B (Aurora), 213A (Aurora), 89-215 (Aurora), AL-1 (Aurora - D05), D05 520 (D05), D05 517 (D05), D05 519 (D05) zone 5 6yr PM 13.33 Days
Continuous		  
12-May-26 08:00 29-May-26 17:00 ATCO TE ATCO RTU/SCADA firewall firmware upgrades at the Primary Control Center and the Secondary Control Center
potential activity due to firmware upgrades, firewall failovers, and site cutover activities		 17.38 Days
Continuous		  
12-May-26 12:00 15-May-26 14:00 ATCO, ENBRIDGE TE ATCO Telecom Equipment, 658s RTU/SCADA (658s Chard) Chard telecom replacing 3.08 Days
Continuous		  
13-May-26 08:00 26-May-26 16:00 ATCO, CNRL, ALBIAN Outage 847s 902T (847s Muskeg River), 919s 908 (919s Hartley) open 908 breaker and 902TD in the Hartley 919S substation for maintenance 13.33 Days
Continuous		  
13-May-26 08:30 14-May-26 16:00 ALTALINK TE 562s Protection & Control (562s Cypress) 562s RAS relay maintenance 31.5 Hours
Daily		  
13-May-26 09:00 14-May-26 15:00 ATCO, ALBIAN Outage 9LJH2 (919s Hartley - 920s Jackpine), 920s 902T (920s Jackpine), 920s 902 (920s Jackpine), 919s 907 (919s Hartley), 920s B1 (920s Jackpine), 920s 902TD (920s Jackpine) isolation of 902T for CNRL to troubleshoot problems on their system 30 Hours
Continuous		  
13-May-26 09:00 14-May-26 17:00 ALTALINK TE 67s RTU/SCADA (67s Stirling) CRU upgrade - supervisory outage to complete upgrades to RTU and alarm splitting 1.33 Days
Daily		  
13-May-26 09:00 14-May-26 17:00 ALTALINK TE 67s Protection & Control (67s Stirling) upgrade CRU - alarm splitting, protection outages on 508L A/B protections to complete scope 1.33 Days
Daily		  
14-May-26 07:00 14-May-26 18:00 ALTALINK Outage 880L (321s Al Rothbauer - 523s Bullshead), 321s 880 (321s Al Rothbauer), 523s 880 (523s Bullshead) re-installing damper on structure 4, re-tying OHSW's on structure 8 11 Hours
Daily		  
14-May-26 08:00 14-May-26 17:00 ALTALINK Outage 77s 552 (77s Sagitawah) 138kV breaker maintenance 9 Hours
Continuous		  
14-May-26 08:00 14-May-26 16:00 ENMAX TE Protection & Control (SS-65) 65 sub 86BF D132 lockout relay protection outage, relays, lockout testing 65RLY240-D132 8 Hours
Continuous		  
14-May-26 08:00 14-May-26 16:00 ALTALINK TE 42s Protection & Control (42s Sarcee) urgent - complete card replacements and firmware upgrade on relay to correct communications failure, 3L B21/79/L8 URD60 out of service 8 Hours
Continuous		  
14-May-26 08:00 14-May-26 11:00 Lethbridge TE 241s Protection & Control (241s Uplands) 241s 138kv bus protection (SEL 487b) outage to add logic for DDR initiate and test output circuits 3 Hours
Continuous		  
14-May-26 09:30 15-May-26 16:00 ATCO TE 840s RTU/SCADA (840s McNeill Station) moving communication and SCADA traffic onto new star link device 30.5 Hours
Continuous		  
14-May-26 12:00 14-May-26 17:00 ALTALINK TE 120s RTU/SCADA (120s Picture Butte) RTU mitigations and reboot 5 Hours
Continuous		 AB-MATL
15-May-26 07:00 15-May-26 17:30 ATCO TE 743s Protection & Control (743s Sarah Lake) blocking 21B/6L126 relay for some settings changes 10.5 Hours
Continuous		  
15-May-26 07:15 17-May-26 18:00 ALTALINK Outage 677L (305s Acheson - 595s Spruce Grove), 305s 677 (305s Acheson), 595s 677 (595s Spruce Grove) transmission line maintenance 2.45 Days
Continuous		  
15-May-26 08:00 18-May-26 16:00 ALTALINK TE 275s RTU/SCADA (275s Jenner) split the existing SCADA VLAN from 1 to 1 and 2

3.33 Days
Continuous		  
15-May-26 08:00 15-May-26 12:00 ENMAX Outage 22.81L (SS-22 - SS-39), 22.2TR (SS-22), 22B138-22.81 (SS-22), 22B138-22BT8 (SS-22), SW85 (SS-22), 39B138-22.81 (SS-39) spring substation washing 4 Hours
Continuous		  
15-May-26 09:00 25-May-26 17:00 BCH, ALTALINK Outage 2L113 (BCH Cranbrook - BCH Natal), 2D23 (BCH Nelway), 2D21 (BCH Natal), 1D22 (BCH Elkford tap) install marker balls 10.33 Days
Continuous		 AB-BC
15-May-26 12:00 15-May-26 18:00 ENMAX Outage 13.82L (SS-13 - SS-22), 22.3TR (SS-22), 22.1TR (SS-22), 13B138-13.82 (SS-13), 22B138-13.82 (SS-22), 22B138-22BT8 (SS-22), SW83 (SS-22), SW84 (SS-22) spring substation washing 6 Hours
Continuous		  
16-May-26 08:00 16-May-26 18:00 ENMAX Outage 21.4TR (SS-21), 15.60L (SS-15 - SS-21), 21.61L (SS-21 - SS-34), 21B69-21.4TR (SS-21), 21B69-21.61 (SS-21), 21B69-15.60 (SS-21) spring substation washing and power factor test - 21PT69-1 10 Hours
Continuous		  
18-May-26 08:00 19-May-26 16:00 ALTALINK TE 370s Protection & Control (370s North Lethbridge) move relay to new City of Lethbridge communication system 1.33 Days
Continuous		  
18-May-26 08:00 19-May-26 17:00 Lethbridge TE 146s Protection & Control (146s Macdonald) protection outages on 146s 667L 'A' & 'B' protection to transfer TPR (teleprotection) circuit from existing JMUX to new SEL ICON 1.38 Days
Continuous		  
18-May-26 08:00 22-May-26 16:00 CMH TE MHS-7 Protection & Control (MHS-7 Brier Park) perform preventative maintenance on BPR-69-B 4.33 Days
Continuous		  
18-May-26 08:00 27-May-26 16:00 ENMAX Outage 1.5TR (SS-1) connect transformer secondary cables to 1B8-1.5TR 9.33 Days
Continuous		  
18-May-26 09:00 19-May-26 20:00 SUNCOR Outage 29PL6-6 (29EDD-1 Millennium - 29EDD-2 Tar Island), 29EDD-2 29PT-2 (29EDD-2 Tar Island), 29EDD-2 29PS-5 (29EDD-2 Tar Island) correct cable stress on 29PT-2 NGR (29PR-1) 1.46 Days
Continuous		  
19-May-26 07:00 01-Jun-26 07:00 EPCOR Outage T1 (Rossdale), 814s T2 (814s Bellamy), R721 (Rossdale), BR722 (Rossdale) LCR demo 13 Days
Continuous		  
19-May-26 07:00 21-May-26 17:00 EPCOR Outage S723 (Strathcona) S723 (SF6) breaker maintenance and CT doble 2.42 Days
Continuous		  
19-May-26 07:00 19-May-26 17:00 EPCOR Outage T2 (Poundmaker), PM2405 (Poundmaker), PM2401 (Poundmaker) TX2 Zone, PMAB2 repair 10 Hours
Continuous		  
19-May-26 07:00 28-Aug-26 17:00 EPCOR TE 987s Protection & Control (987s Clover Bar) protection blocking - relay maintenance and bus differential upgrade project 101.42 Days
Continuous		  
19-May-26 07:30 21-May-26 17:30 ALTALINK RB 759L (87s Gaetz - 276s Prentiss) prep for component replacement on 759L77-139 2.42 Days
Daily		  
19-May-26 07:30 21-May-26 17:30 ALTALINK RB 775L (276s Prentiss - 535s Joffre) prep for component replacement on 759L77-139 2.42 Days
Daily		  
19-May-26 07:30 23-May-26 15:00 CMH Outage MHS-3 MH69-T32 (MHS-3 Southridge), MHS-3 MH69-306 (MHS-3 Southridge) reconditioning oil on transformer MH69-T32 at MHS-3S Southridge substation 4.31 Days
Continuous		  
19-May-26 08:00 21-May-26 16:00 ATCO RB 7L75 (ATC 793s West Peace River - 800s Friedenstal) walk up and climbing inspection 2.33 Days
Continuous		  
19-May-26 08:00 21-May-26 16:00 ALTALINK Outage 37s T3 (37s North Calder) P&C upgrades (37s14) 2.33 Days
Continuous		  
19-May-26 08:00 21-May-26 17:00 Lethbridge TE 181s Protection & Control (181s Chinook) transfer TPR (teleprotection) circuits from existing JMUX to new SEL ICON 2.38 Days
Continuous		  
19-May-26 08:00 21-May-26 17:00 Lethbridge TE 146s Protection & Control (146s Macdonald), 241s Protection & Control (241s Uplands) protection outages on 241s and 146s 813L 'B' protection to transfer TPR (teleprotection) circuit from existing JMUX to new SEL ICON
 2.38 Days
Continuous		  
19-May-26 08:00 20-May-26 16:00 ENMAX Outage 13.82L (SS-13 - SS-22), 22B138-13.82 (SS-22), 13B138-13.82 (SS-13) breaker maintenance 1.33 Days
Continuous		  
19-May-26 08:00 21-May-26 16:00 ALTALINK TE 207s RTU/SCADA (207s Pinedale), AltaLink Telecom Equipment firewall replacement , MPLS 7705A upgrade 2.33 Days
Continuous		  
19-May-26 08:00 19-May-26 09:05 ALTALINK Outage 254s 172E (254s Coaldale), 83s 172W (83s Taber), 172L (254s Coaldale - 172EL tap), 172L (83s Taber - 172EL tap) 172L outage to facilitate the opening of 172EL1 which is required to be opened de-energized. 65 Mins
Continuous		  
19-May-26 08:00 22-May-26 18:00 ALTALINK RB 601L (230s Wardlow - 275s Jenner) O/H reties and insulator replacements 3.42 Days
Daily		  
19-May-26 08:00 21-May-26 16:00 ALTALINK TE AltaLink Telecom Equipment firewall upgrade , MPLS 7705A and 7705B node upgrade 2.33 Days
Continuous		  
19-May-26 08:00 21-May-26 16:00 ATCO RB 7L34 (815s Goodfare - 886s Updike) walk up and climbing inspection 2.33 Days
Continuous		  
19-May-26 08:00 19-May-26 17:00 ALTALINK TE 58s RTU/SCADA (58s Edson), AltaLink Telecom Equipment MPLS firmware upgrade and nodes C andD, firewall upgrade 9 Hours
Continuous		  
19-May-26 08:00 19-May-26 16:00 ALTALINK TE 358s RTU/SCADA (358s Amoco Brazeau) split the existing SCADA VLAN from 1 to 1 and 2 8 Hours
Continuous		  
19-May-26 08:00 21-May-26 16:00 ALTALINK TE 267s RTU/SCADA (267s Killarney Lake) RTU database update 2.33 Days
Continuous		  
19-May-26 08:00 21-May-26 16:00 ALTALINK TE AltaLink RTU/SCADA (AltaLink) AESO is taking a full building power outage that will de-energize all AltaLink equipment on site, decision was made to also de-energize 9485R AESO Radio equipment as well as it feeds 9010R and would be running on battery power during an outage. 2.33 Days
Continuous		  
19-May-26 08:00 19-May-26 16:00 ENMAX TE Protection & Control (SS-65) 65 sub 86BF D131 lockout relay protection outage - relays, lockout testing 65RLY240-D131 8 Hours
Continuous		  
19-May-26 08:00 20-May-26 16:00 ENMAX Outage 10.2TR (SS-10) tap changer inspection - 10.2-TC, reversing switch check, oil sampling MT, TC, gas monitor maintenance 1.33 Days
Continuous		  
19-May-26 08:00 22-May-26 16:00 ENMAX Outage 3.3TR (SS-3) transformer power factor test, secondary cable test, maintenance, relay fault pressure test. oil sampling MT, TC 3.33 Days
Continuous		  
19-May-26 08:00 20-May-26 16:00 ENMAX Outage 41.1TR (SS-41) 41 SUB - CT terminal block replacement 1.33 Days
Continuous		  
19-May-26 08:00 20-May-26 16:00 ENMAX TE Protection & Control (SS-41) 41 sub 138 kV zone 31 bus differential protection outage - 41 SUB - CT terminal block replacement 1.33 Days
Daily		  
19-May-26 08:00 22-May-26 16:00 ALTALINK TE 370s Protection & Control (370s North Lethbridge) move 2411 in south building to new city of Lethbridge comm system 3.33 Days
Continuous		  
19-May-26 08:00 21-May-26 16:00 ALTALINK TE 37s Protection & Control (37s North Calder) protection alarm cutovers 2.33 Days
Continuous		  
19-May-26 08:00 19-May-26 16:00 ENMAX Outage 1.4TR (SS-1) replace the PRD junction boxes 8 Hours
Continuous		  
19-May-26 08:10 22-May-26 18:30 ALTALINK, ACCIONA Outage 172EL (139s Hillridge - 172L tap) perform minor preventative maintenance. 3.43 Days
Continuous		  
19-May-26 09:00 19-May-26 17:00 ATCO Outage 9L16 (755s Cordel - 972s Tinchebray), 755s 904 (755s Cordel), 755s 905 (755s Cordel), 972s 903 (972s Tinchebray) Disconnect 9L16 from existing A-frame deadend and 9L16D2 (to be renamed 9L86D1)
Restore bus leave renamed 9L86D1 open for future line connection.
 8 Hours
Continuous		  
19-May-26 09:00 29-May-26 17:00 ATCO, GREENGATEP Outage 9L16 (755s Cordel - 972s Tinchebray), 755s 905 (755s Cordel), 755s 904 (755s Cordel) disconnect 9L16 from existing A-frame deadend and 9L16D2 (to be renamed 9L86D1)
restore bus leave renamed 9L86D1 open for future line connection
 10.33 Days
Continuous		  
19-May-26 09:00 29-May-26 17:00 ATCO TE 755s Protection & Control (755s Cordel), 755s RTU/SCADA (755s Cordel) protection updates and end to end testing 10.33 Days
Continuous		  
19-May-26 09:00 29-May-26 17:00 ATCO TE 972s Protection & Control (972s Tinchebray), 972s RTU/SCADA (972s Tinchebray) 9L16 protection setting changes including updates at 755s and 620s 10.33 Days
Continuous		  
19-May-26 09:00 23-May-26 17:00 BCH, BPA Outage 5L52 (BPA Custer - BCH Ingledow) doble and inspection 5CB5 4.33 Days
Continuous		 AB-BC
19-May-26 09:00 20-May-26 17:00 BCH, BPA Outage 5L52 (BPA Custer - BCH Ingledow) Glass replacement 1.33 Days
Continuous		 AB-BC
19-May-26 09:00 19-May-26 17:00 BCH Outage T4 (BCH Natal) Natal substation replacement and ETM install 8 Hours
Continuous		 AB-BC
19-May-26 09:00 29-May-26 17:00 ATCO, CapitalPower TE 620s 240kV Bus (620s Goldeye), 620s Protection and Control (620s Goldeye) protection updates and testing at 620S Goldeye - 9L16 3 terminal testing between Cordel-Goldeye-Tinchebray 10.33 Days
Continuous		  
19-May-26 10:00 19-May-26 17:00 ALTALINK TE 405s RTU/SCADA (405s Waupisoo) RTU database update 7 Hours
Continuous		  
19-May-26 10:00 19-May-26 15:00 BCH Outage 2L294 (BCH A. A. Lambert - BCH Nelway) replace severely cracked cross arm 5 Hours
Continuous		 AB-BC
19-May-26 12:00 21-May-26 17:00 ALTALINK TE 103s Protection & Control (103s Goose Lake) PRC005 maintenance - upgrade DSP cards and firmware updates to relays 2.21 Days
Daily		  
19-May-26 12:00 21-May-26 17:00 ALTALINK TE 396s Protection & Control (396s Pincher Creek) PRC005 maintenance - upgrade DSP cards and firmware updates to relays 2.21 Days
Daily		  
19-May-26 13:00 21-May-26 16:00 ALTALINK Outage 851L (253s Blackie - 525s Carseland), 525s 851X (525s Carseland), 253s 851W (253s Blackie) PRC5 breaker maintenance - 525s851X 2.13 Days
Continuous		  
19-May-26 13:30 21-May-26 17:00 ALTALINK Outage 17s T1 (17s Benalto) install bird cover on 25 kV bus, regulator, breakers and switches, replace switch signs in 25 kV bus. 17s55 and 80 fused disconnects to be replaced, no change to fuse sizes or SLD 2.15 Days
Continuous		  
19-May-26 15:00 21-May-26 16:30 ALTALINK Outage 71s 552 (71s Lamoureux) 138 kV breaker maintenance 2.06 Days
Continuous		  
19-May-26 23:00 21-May-26 07:00 ALTALINK, TRANSALTA Outage 250p T1 (250p Bighorn Plant) maintenance 1.33 Days
Continuous		  
20-May-26 07:00 21-May-26 17:00 ALTALINK Outage 216s T3 (216s Knightsbridge), 216s 552 (216s Knightsbridge) T3 metering module replacement 1.42 Days
Continuous		  
20-May-26 07:00 21-May-26 07:00 ALTALINK, TRANSALTA Outage 250p T2 (250p Bighorn Plant) maintenance 24 Hours
Continuous		  
20-May-26 07:00 28-May-26 17:00 ALTALINK TE 275s RTU/SCADA (275s Jenner) 275s Jenner RTU update for switch replacement 8.42 Days
Daily		  
20-May-26 07:15 20-May-26 12:45 ALTALINK Outage 37s 726E (37s North Calder), 726L (37s North Calder - 71s Lamoureux) transmission line maintenance 5.5 Hours
Continuous		  
20-May-26 07:30 20-May-26 17:00 ALTALINK Outage 267s T1 (267s Killarney Lake) transformer and breaker maintenance 9.5 Hours
Continuous		  
20-May-26 08:00 20-May-26 17:00 ALTALINK Outage 90L (32s Barrier - 115s Mount Allan) 90L Replacing insulators on structure 48 9 Hours
Continuous		  
20-May-26 08:00 20-May-26 16:00 ALTALINK TE AltaLink Telecom Equipment, 445s RTU/SCADA (445s Elk River) radio repair work 8 Hours
Continuous		  
20-May-26 08:00 21-May-26 17:00 ATCO RB 9L84 (934s Blackfly - 977s Salt Creek) replace 3 damaged insulator strings on 9L84 structure 47 -
live line techniques		 1.38 Days
Continuous		  
20-May-26 08:00 22-May-26 17:00 ATCO TE 957s Protection & Control (957s McClelland) relay work - isolate 21A & B/ L9900 relays 2.38 Days
Continuous		  
20-May-26 08:00 20-May-26 16:30 ALTALINK Outage 77s 652 (77s Sagitawah) 138kV breaker maintenance 8.5 Hours
Continuous		  
20-May-26 08:00 20-May-26 16:00 ALTALINK TE 359s RTU/SCADA (359s Esso West Pembina) split the existing SCADA VLAN from 1 to 1 and 2

8 Hours
Continuous		  
20-May-26 08:00 20-May-26 16:00 ALTALINK TE 207s Protection & Control (207s Pinedale) card replacement 8 Hours
Continuous		  
20-May-26 08:00 20-May-26 16:00 ALTALINK TE 58s Protection & Control (58s Edson) card replacement 8 Hours
Continuous		  
20-May-26 08:00 20-May-26 16:00 ENMAX TE Protection & Control (SS-65) 65 sub 86BF D130 lockout relay protection outage - relays, lockout testing 65RLY240-D130 8 Hours
Continuous		  
20-May-26 08:30 20-May-26 18:00 ALTALINK Outage 242s T1 (242s Flat Lake) replace T1 metering equipment, change metering CT ratios 9.5 Hours
Continuous		  
20-May-26 08:30 20-May-26 18:00 ALTALINK, ALPAC Outage 796L (282s Grassland - 796AL tap), 282s T1 (282s Grassland (Alpac)), 282s 50 (282s Grassland), 282s H1 (282s Grassland), 282s 18-110-DS (282s Grassland) maintenance 9.5 Hours
Continuous		  
20-May-26 08:30 20-May-26 18:00 ALTALINK Outage 796L (405s Waupisoo - 796AL tap), 405s 796 (405s Waupisoo) PRC5 breaker maintenance and replace failing tank heaters 9.5 Hours
Continuous		  
20-May-26 08:30 20-May-26 18:00 ALTALINK TE 405s Protection & Control (405s Waupisoo) maintenance on 405s 796L (L7) line protection 9.5 Hours
Continuous		  
20-May-26 09:00 28-May-26 17:00 ALTALINK Outage 275s T2 (275s Jenner), 275s 46 (275s Jenner), 275s 2252 (275s Jenner) maintenance 8.33 Days
Continuous		  
20-May-26 09:00 21-May-26 17:00 BCH Outage T3 (BCH Natal) inspection/doble 1.33 Days
Continuous		 AB-BC
20-May-26 09:00 26-May-26 16:00 ATCO TE ATCO Telecom Equipment, 865s RTU/SCADA (865s Saddlehills) SaddleHills_S-Telecom- Telecom work in coordination with P&C upgrade. Short RTU outages through the outage duration (5-10mins).
May 25th RTU outage from 10am-2pm.		 6.29 Days
Continuous		  
20-May-26 09:00 20-May-26 17:00 ALTALINK TE 405s RTU/SCADA (405s Waupisoo) RTU database update 8 Hours
Continuous		  
20-May-26 09:00 20-May-26 17:30 ALTALINK TE 242s RTU/SCADA (242s Flat Lake) SCADA/supervisory outage to complete T1 meter module CRU upgrade 8.5 Hours
Continuous		  
20-May-26 09:00 20-May-26 16:00 ATCO RB 7L159 (770s Three Hills - 7L159 tap), 7L159 (948s Heatburg - 7LA159 tap) telecom work 1-518007 7 Hours
Continuous		  
20-May-26 10:00 22-May-26 17:00 ATCO TE ATCO Telecom Equipment Tower Reinforcement Project: Outage to happen on May 21. May be pushed to May 22 due to weather.
2 Seperate outages
1. Cordel/Tinchebray Radio:
RAS A 134, 138, 139
7L50 A&B O/L
9LA16 A&B
9LA16 A
9L159 A
RAS #211, #215 A&B
9L27 B
9L16 A
RAS 134 B
9L20 RAS B
9L20 A

2.
9L948 B
2.29 Days
Continuous		  
20-May-26 10:00 21-May-26 15:00 ATCO TE 741s Protection & Control (741s Fox Creek), 741s RTU/SCADA (741s Fox Creek) 741S Fox Creek 21B/7L90 deficiency - fixing relay mis-coordination, BMS DNP3 index mismatch - station controller update 29 Hours
Continuous		  
21-May-26 07:15 30-May-26 17:45 ALTALINK Outage 1202L (89s Ellerslie - 320p Keephills) Urgent repair, transmission line maintenance 9.44 Days
Continuous		  
21-May-26 07:30 26-May-26 12:30 ALTALINK Outage 157s 23 (157s Lac La Biche), 157s 788N (157s Lac La Biche), 157s 728W (157s Lac La Biche), 157s 652 (157s Lac La Biche), 157s C1 (157s Lac La Biche), 157s 3 (157s Lac La Biche), 157s T1 (157s Lac La Biche), 157s 138kV Bus 1 (157s Lac La Biche) Install new switch/breaker & close 157s Open Point 'A' 5.21 Days
Continuous		  
21-May-26 07:30 30-May-26 17:30 ALTALINK, EPCOR RB 909L (310p Sundance - 665s Dome) safety requirement for 1202L GOI 9.42 Days
Continuous		  
21-May-26 08:00 21-May-26 16:00 ALTALINK TE 428s RTU/SCADA (428s Namaka) add and test T2 tap changer controls with ACC 8 Hours
Continuous		  
21-May-26 08:00 21-May-26 16:30 ALTALINK Outage 77s 752 (77s Sagitawah) breaker maintenance 8.5 Hours
Continuous		  
21-May-26 08:00 21-May-26 16:00 ALTALINK TE 212s RTU/SCADA (212s Lacombe) split the existing SCADA VLAN from 1 to 1 and 2

8 Hours
Continuous		  
21-May-26 08:00 21-May-26 16:00 ENMAX TE Protection & Control (SS-2) 2 sub 86 BF-D93 protection outage - relays, lockout testing 8 Hours
Continuous		  
21-May-26 08:00 22-May-26 16:00 ENMAX Outage 6.1TR (SS-6) tap changer inspection - 6.1-TC, reversing switch check, oil sampling MT, TC, bushing 1.33 Days
Continuous		  
21-May-26 08:00 21-May-26 18:00 ENMAX Outage 16.63L (SS-16 - SS-36), 16.60L (SS-16 - SS-34), 16.2TR (SS-16), 16B69-16.63 (SS-16), 16B69-16.60 (SS-16), 16MD69-16.2TR (SS-16) 16 sub SW65 Switch maintenance 10 Hours
Continuous		  
21-May-26 08:00 21-May-26 16:00 ALTALINK TE AltaLink Telecom Equipment test the radio paths 8 Hours
Continuous		  
21-May-26 08:00 26-May-26 12:00 ATCO, ALTALINK RB 788L (898s Heart Lake - 788AL tap) Altalink request 5.17 Days
Continuous		  
21-May-26 08:00 21-May-26 16:00 ENMAX Outage 162B138-RB94 (SS-162) breaker maintenance and breaker SF6 gas sample 8 Hours
Continuous		  
21-May-26 08:00 21-May-26 18:00 ENMAX Outage 38.3TR (SS-38) 38.3TR secondary cable replacement - punchlist item 10 Hours
Continuous		  
21-May-26 08:00 21-May-26 11:00 Lethbridge TE 181s Protection & Control (181s Chinook) 181s 138KV bus protection (GE B90) outage to add logic for DDR initiate and test output circuit.
 3 Hours
Continuous		  
21-May-26 08:30 21-May-26 17:00 ALTALINK TE 405s RTU/SCADA (405s Waupisoo) RTU database update 8.5 Hours
Continuous		  
21-May-26 11:00 21-May-26 14:00 Lethbridge TE 674s Protection & Control (674s Bowron) 674s 725LW A protection (SEL 411L) outage
to enable fault locator and test SCADA points		 3 Hours
Continuous		  
21-May-26 12:00 21-May-26 16:00 ALTALINK Outage 428s T2 (428s Namaka), 428s 652 (428s Namaka) add and test tap changer controls from ACC 4 Hours
Continuous		  
22-May-26 07:15 28-May-26 17:45 ALTALINK Outage 890L (58s Edson - 207s Pinedale), 58s 890 (58s Edson), 207s 890 (207s Pinedale) transmission line maintenance 6.44 Days
Continuous		  
22-May-26 08:00 22-May-26 17:00 ALTALINK TE 44s RTU/SCADA (44s Bearspaw Plant) firewall upgrade and SCADA SUB LAN work 9 Hours
Continuous		  
22-May-26 08:00 22-May-26 16:00 ALTALINK TE AltaLink RTU/SCADA (AltaLink) wiring 2 intrusion alarms from the door contact device to the SCADA D25 in the AECC data room 8 Hours
Continuous		  
22-May-26 08:00 22-May-26 16:00 ALTALINK TE AltaLink Telecom Equipment test the radio paths 8 Hours
Continuous		  
22-May-26 08:00 22-May-26 16:00 ALTALINK TE AltaLink Telecom Equipment add intrusion alarms to the SCADA RTU D25 8 Hours
Continuous		  
22-May-26 08:00 22-May-26 18:00 ALTALINK Outage 254s T1 (254s Coaldale) URGENT: Techs to replace failing LTC Beckwidth controller. 10 Hours
Continuous		  
22-May-26 08:30 22-May-26 11:30 ALTALINK RB 760L (163s Amoco Empress - 760AL tap) reclosing disabled for telecom permit 1-00518079 3 Hours
Daily		  
22-May-26 09:00 22-May-26 11:00 ATCO TE ATCO Telecom Equipment, 959s RTU/SCADA (959s Lanfine), 910s RTU/SCADA (910s Excel) Lanfine_S-Telecom- UPGRADING LANFINE NET 11 AND NET 2 SAR TO V21, THEN V22
2 SEPARATE OUTAGES IMPACTING THE FOLLOWING TRAFFIC FOR APPROX 1 HOUR EACH:
OUTAGE 1: RAS A #134, RAS A&B #201 THERMAL, 7L760 A&B, RAS 204 A&B, 7LC760 A&B
OUTAGE 2:RAS B #134 - NEVIS / BUFFALO BIRD
 2 Hours
Continuous		  
22-May-26 09:00 22-May-26 11:00 ATCO RB 7L760 (767s Oyen - 7LC760 tap), 7L760 (7LA760 tap - 7LC760 tap) reclosing disabled for telecom permit 1-00518079 2 Hours
Continuous		  
22-May-26 09:00 22-May-26 16:00 ALTALINK TE 254s RTU/SCADA (254s Coaldale) URGENT: Supervisory outage required for 254sT1 LTC controller replacement.
~15min loss of visibility while updating RTU configs.		 7 Hours
Continuous		  
22-May-26 13:00 22-May-26 15:00 ATCO TE ATCO Telecom Equipment Ksituan_S-Telecom- KSITUAN SUB A AND B SAR OS UPGRADE TO V21, THEN V22
2 SEPARATE OUTAGES TO THE FOLLOWING TRAFFIC FOR APPROX 1 HR EACH:
OUTAGE 1: 7L10 BREAKER FAIL , 7L73 & 7L68 RAS A, 7L68 RAS A ,7L68/7L75/7L73/7L75 RAS A
OUTAGE 2:7L73/7L757L68 RAS B		 2 Hours
Continuous		  
22-May-26 16:05 22-May-26 17:35 ALTALINK, ACCIONA Outage 254s 172E (254s Coaldale), 83s 172W (83s Taber), 172EL (139s Hillridge - 172L tap), 172L (254s Coaldale - 172EL tap), 172L (83s Taber - 172EL tap) 172L out of service to close 172EL1 90 Mins
Continuous		  
22-May-26 23:00 23-May-26 07:00 ALTALINK Outage 964s T3 (964s Pigeon Lake) urgent - replace failed PT on 25 kV bus 8 Hours
Continuous		  

Prepared On:   2026-05-13   17:45:25

This document and the information contained herein are based upon information and data which by their nature contain a degree of uncertainty and are subject to change. In addition, this document may contain information and data from public sources and/or third parties, which have been assumed to be accurate and complete and have not been verified. Accordingly, the Independent System Operator, operating as the Alberta Electric System Operator (the "AESO") makes no warranty, representation or guarantee, express or implied, with respect to this document or the information contained herein, including, but not limited to, any warranty, representation or guarantee of accuracy, completeness, timeliness, reliability, availability, absence of computer virus, non- infringement, merchantability or suitability for any purpose. Under no circumstances will the AESO, its members, officers, employees, contractors or agents, or any of their respective affiliates, be liable for any errors or omissions in, or any losses, damages or claims whatsoever, whether in contract, tort or otherwise, arising from use of or reliance upon, this document or any information contained herein.

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