1 00:00:00,000 --> 00:00:00,900 In this lesson, 2 00:00:00,900 --> 00:00:03,390 we'll discuss powering of our data centers. 3 00:00:03,390 --> 00:00:04,230 Now, data centers 4 00:00:04,230 --> 00:00:06,150 are the beating heart of our digital world, 5 00:00:06,150 --> 00:00:08,250 and keeping them powered under all circumstances 6 00:00:08,250 --> 00:00:11,100 is crucial for the success of our business operations. 7 00:00:11,100 --> 00:00:13,590 To ensure our data centers always have power available, 8 00:00:13,590 --> 00:00:15,300 we must architect our infrastructure 9 00:00:15,300 --> 00:00:17,760 with multiple forms of redundant power. 10 00:00:17,760 --> 00:00:20,100 Now, when it comes to power, there are five key terms 11 00:00:20,100 --> 00:00:22,290 that describe the current state of the power being received 12 00:00:22,290 --> 00:00:23,430 by our systems. 13 00:00:23,430 --> 00:00:27,480 These conditions include things like surges, spikes, sags, 14 00:00:27,480 --> 00:00:30,390 undervoltage events, and full power loss events. 15 00:00:30,390 --> 00:00:32,070 First, we have a surge. 16 00:00:32,070 --> 00:00:33,450 Now, a surge in electrical power 17 00:00:33,450 --> 00:00:35,910 means that there is a small and unexpected increase 18 00:00:35,910 --> 00:00:38,010 in the amount of voltage that's being provided. 19 00:00:38,010 --> 00:00:39,660 So here in the United States, 20 00:00:39,660 --> 00:00:42,720 our default power supply uses 120 volts. 21 00:00:42,720 --> 00:00:45,510 Now, if that went up to 125 or 130 volts 22 00:00:45,510 --> 00:00:47,610 instead of remaining at 120 volts, 23 00:00:47,610 --> 00:00:49,290 we would call this a slight increase 24 00:00:49,290 --> 00:00:52,170 in the amount of power being received as a surge. 25 00:00:52,170 --> 00:00:53,970 Second, we have a spike. 26 00:00:53,970 --> 00:00:56,100 Now, a spike is a short transient voltage 27 00:00:56,100 --> 00:00:58,320 that's usually going to be caused by a short circuit, 28 00:00:58,320 --> 00:01:00,300 a tripped circuit breaker, a power outage, 29 00:01:00,300 --> 00:01:01,770 or a lightning strike. 30 00:01:01,770 --> 00:01:05,129 With a spike, you might see a default voltage of 120 volts 31 00:01:05,129 --> 00:01:09,600 rise all the way up to 150 volts or 175 volts or even more. 32 00:01:09,600 --> 00:01:11,430 To protect against a surge or a spike, 33 00:01:11,430 --> 00:01:13,440 your systems should utilize a surge protector 34 00:01:13,440 --> 00:01:14,580 or line conditioner 35 00:01:14,580 --> 00:01:16,170 which will be able to remove any power levels 36 00:01:16,170 --> 00:01:18,030 that are higher than about 120 volts 37 00:01:18,030 --> 00:01:20,760 that are used by default here in the United States. 38 00:01:20,760 --> 00:01:22,380 Third, we have a sag. 39 00:01:22,380 --> 00:01:23,850 Now, a sag in electrical power 40 00:01:23,850 --> 00:01:26,190 means that there is a small and unexpected decrease 41 00:01:26,190 --> 00:01:28,260 in the amount of voltage that's being provided. 42 00:01:28,260 --> 00:01:30,120 A sag is very similar to a surge, 43 00:01:30,120 --> 00:01:31,650 but it's actually an opposite 44 00:01:31,650 --> 00:01:33,180 because instead of the voltage going up, 45 00:01:33,180 --> 00:01:34,740 it's actually going down. 46 00:01:34,740 --> 00:01:37,167 Usually, a sag will only occur for a short period of time, 47 00:01:37,167 --> 00:01:39,570 and if the decreased voltage remains fairly close 48 00:01:39,570 --> 00:01:41,670 to your default level of 120 volts, 49 00:01:41,670 --> 00:01:43,500 then your computers may not even lose power 50 00:01:43,500 --> 00:01:45,600 or go offline during that sag. 51 00:01:45,600 --> 00:01:48,180 For example, it's common to see sags drop the voltage 52 00:01:48,180 --> 00:01:52,620 from 120 volts down to 117 or 115 volts instead. 53 00:01:52,620 --> 00:01:54,270 And at these levels, your computers 54 00:01:54,270 --> 00:01:56,160 will remain online and operational 55 00:01:56,160 --> 00:01:58,050 because there's still enough power to run them. 56 00:01:58,050 --> 00:02:00,540 But it could damage your hardware components over time, 57 00:02:00,540 --> 00:02:01,373 and so again, 58 00:02:01,373 --> 00:02:03,270 you want to use something like a line conditioner 59 00:02:03,270 --> 00:02:05,700 to bring that voltage back up to the 120 volts 60 00:02:05,700 --> 00:02:08,070 that you're expecting to get by your systems. 61 00:02:08,070 --> 00:02:10,199 Fourth, we have an undervoltage event. 62 00:02:10,199 --> 00:02:11,460 Now, an undervoltage event, 63 00:02:11,460 --> 00:02:13,560 which used to be referred to as a brownout, 64 00:02:13,560 --> 00:02:15,900 occurs when the voltage is reduced to lower levels, 65 00:02:15,900 --> 00:02:18,540 and it usually occurs for a longer period of time. 66 00:02:18,540 --> 00:02:20,160 For example, if you're expecting 67 00:02:20,160 --> 00:02:21,990 to receive 120 volts of power 68 00:02:21,990 --> 00:02:25,200 but the voltage level drops down to 70 or 80 volts instead, 69 00:02:25,200 --> 00:02:27,690 this would be considered an undervoltage event. 70 00:02:27,690 --> 00:02:29,610 In this case, the voltage will be too low 71 00:02:29,610 --> 00:02:31,260 to continue operating your systems, 72 00:02:31,260 --> 00:02:34,560 so your systems will go offline and power themselves down. 73 00:02:34,560 --> 00:02:36,900 Fifth, we have a power loss event. 74 00:02:36,900 --> 00:02:39,570 Now, a power loss event, also called a power failure 75 00:02:39,570 --> 00:02:42,480 or referred to by its legacy name of a blackout, 76 00:02:42,480 --> 00:02:44,580 will occur whenever there's a total loss of power 77 00:02:44,580 --> 00:02:46,350 for a given period of time. 78 00:02:46,350 --> 00:02:48,660 For example, if you're sitting in your home office 79 00:02:48,660 --> 00:02:51,210 and the power is completely lost for a minute or two, 80 00:02:51,210 --> 00:02:54,090 that would be considered a complete power loss event. 81 00:02:54,090 --> 00:02:55,560 With a complete power loss event, 82 00:02:55,560 --> 00:02:57,090 it's really important that you're aware 83 00:02:57,090 --> 00:02:58,380 that when the power's restored, 84 00:02:58,380 --> 00:03:00,480 it can actually cause a power spike to occur, 85 00:03:00,480 --> 00:03:02,670 and this can damage your systems too. 86 00:03:02,670 --> 00:03:04,260 So now that you have a good understanding 87 00:03:04,260 --> 00:03:05,670 of the five different power conditions 88 00:03:05,670 --> 00:03:06,780 that you may experience, 89 00:03:06,780 --> 00:03:10,230 including surges, spikes, sags, undervoltage events, 90 00:03:10,230 --> 00:03:12,060 and full loss of power events, 91 00:03:12,060 --> 00:03:14,460 let's take a look at the different types of robust systems 92 00:03:14,460 --> 00:03:16,740 that can help us to keep our data centers up and running 93 00:03:16,740 --> 00:03:18,690 by focusing on line conditioners, 94 00:03:18,690 --> 00:03:20,520 uninterruptible power supply systems, 95 00:03:20,520 --> 00:03:22,710 generators, and power distribution centers 96 00:03:22,710 --> 00:03:24,630 to better understand how these components help 97 00:03:24,630 --> 00:03:27,120 to ensure the high availability and reliability 98 00:03:27,120 --> 00:03:29,910 of our systems located within our data centers. 99 00:03:29,910 --> 00:03:32,130 Now first, we have a line conditioner. 100 00:03:32,130 --> 00:03:33,570 A line conditioner is used 101 00:03:33,570 --> 00:03:35,340 to overcome any minor fluctuations 102 00:03:35,340 --> 00:03:37,920 in the power being received by the given system. 103 00:03:37,920 --> 00:03:39,570 A line conditioner is going to be used 104 00:03:39,570 --> 00:03:41,910 to continue powering your systems with clean power 105 00:03:41,910 --> 00:03:44,100 even in the face of a surge, a sag, 106 00:03:44,100 --> 00:03:46,530 or even a more pronounced undervoltage event. 107 00:03:46,530 --> 00:03:47,850 Without a line conditioner, 108 00:03:47,850 --> 00:03:49,140 these types of power conditions 109 00:03:49,140 --> 00:03:51,240 could cause unexpected system behavior 110 00:03:51,240 --> 00:03:53,880 or the degradation of your hardware over time. 111 00:03:53,880 --> 00:03:55,680 But by using a line conditioner, 112 00:03:55,680 --> 00:03:56,730 we can automatically adjust 113 00:03:56,730 --> 00:03:58,260 the power signal being received 114 00:03:58,260 --> 00:04:00,630 as an undervoltage or overvoltage condition 115 00:04:00,630 --> 00:04:01,500 and then change it back 116 00:04:01,500 --> 00:04:03,570 to the standard power level of our systems 117 00:04:03,570 --> 00:04:04,890 that they're expecting to receive 118 00:04:04,890 --> 00:04:06,720 in order to prevent damaging our systems 119 00:04:06,720 --> 00:04:08,520 or their associated hardware. 120 00:04:08,520 --> 00:04:11,010 A line conditioner is a great addition to your systems, 121 00:04:11,010 --> 00:04:12,840 but they're not going to keep your systems running 122 00:04:12,840 --> 00:04:15,540 if you're experiencing a significant undervoltage event 123 00:04:15,540 --> 00:04:17,910 or a complete power failure event. 124 00:04:17,910 --> 00:04:20,880 Second, we have an uninterruptible power supply. 125 00:04:20,880 --> 00:04:24,480 Now, an uninterruptible power supply, also called a UPS, 126 00:04:24,480 --> 00:04:27,120 is a device that provides emergency power to a system 127 00:04:27,120 --> 00:04:29,880 when the normal input power source has failed. 128 00:04:29,880 --> 00:04:32,340 A UPS also provides line conditioner functions 129 00:04:32,340 --> 00:04:34,680 on your behalf, as well as providing a battery backup 130 00:04:34,680 --> 00:04:36,990 to maintain a consistent power level to your systems, 131 00:04:36,990 --> 00:04:38,550 even when a complete power failure 132 00:04:38,550 --> 00:04:40,620 of the power source has occurred. 133 00:04:40,620 --> 00:04:43,200 While a UPS is a great device to use in your architecture 134 00:04:43,200 --> 00:04:45,450 to ensure your systems can remain online at all times, 135 00:04:45,450 --> 00:04:48,570 it is important to remember that most UPS units 136 00:04:48,570 --> 00:04:51,510 will only provide 15 to 60 minutes of power 137 00:04:51,510 --> 00:04:53,400 during a complete power failure. 138 00:04:53,400 --> 00:04:56,010 So these UPS units are really designed 139 00:04:56,010 --> 00:04:58,110 to help prevent data loss or hardware damage 140 00:04:58,110 --> 00:05:00,870 during a sudden or short-duration power loss event 141 00:05:00,870 --> 00:05:02,610 and not going to be something that's going to help you 142 00:05:02,610 --> 00:05:04,650 for the long-term power outages. 143 00:05:04,650 --> 00:05:06,630 So this brings us to our third thing, 144 00:05:06,630 --> 00:05:08,310 which is known as a generator. 145 00:05:08,310 --> 00:05:09,510 A generator is a machine 146 00:05:09,510 --> 00:05:12,150 that converts mechanical energy into electrical energy 147 00:05:12,150 --> 00:05:13,560 for use in an external circuit 148 00:05:13,560 --> 00:05:16,260 through the process of electromagnetic induction. 149 00:05:16,260 --> 00:05:17,970 Now, a backup generator should be installed 150 00:05:17,970 --> 00:05:20,430 as part of your emergency power system architecture 151 00:05:20,430 --> 00:05:22,740 so that when there's an outage of your regular power supply 152 00:05:22,740 --> 00:05:23,910 for the electric grid, 153 00:05:23,910 --> 00:05:25,590 the generator will be able to take over 154 00:05:25,590 --> 00:05:27,120 and provide power to your devices 155 00:05:27,120 --> 00:05:29,040 for an extended period of time. 156 00:05:29,040 --> 00:05:31,410 Now, some smaller generators can provide just enough power 157 00:05:31,410 --> 00:05:33,030 for things like emergency lighting, 158 00:05:33,030 --> 00:05:34,920 while larger commercial backup generators 159 00:05:34,920 --> 00:05:36,570 can actually power your entire building 160 00:05:36,570 --> 00:05:39,690 or at least large portions of your building and its systems. 161 00:05:39,690 --> 00:05:42,270 Generators are going to come in three main varieties, 162 00:05:42,270 --> 00:05:43,980 portable gas engine generators, 163 00:05:43,980 --> 00:05:45,330 permanently installed generators, 164 00:05:45,330 --> 00:05:47,340 and battery inverter generators. 165 00:05:47,340 --> 00:05:49,020 Now, a portable gas engine generator 166 00:05:49,020 --> 00:05:51,000 is the least expensive type to operate 167 00:05:51,000 --> 00:05:53,550 because it usually uses just a small gasoline engine 168 00:05:53,550 --> 00:05:56,550 to convert the mechanical motion into electrical power. 169 00:05:56,550 --> 00:05:59,070 These generators tend to be smaller and more portable, 170 00:05:59,070 --> 00:06:00,360 but they also can't support 171 00:06:00,360 --> 00:06:02,250 providing high levels of power either, 172 00:06:02,250 --> 00:06:04,080 so they can't be used to power an entire building 173 00:06:04,080 --> 00:06:05,820 like a large generator would. 174 00:06:05,820 --> 00:06:08,250 With a portable gas engine generator, you're going to find 175 00:06:08,250 --> 00:06:10,080 that they tend to be very noisy when they're operating 176 00:06:10,080 --> 00:06:12,000 because of that gas engine being used, 177 00:06:12,000 --> 00:06:12,840 and this also means 178 00:06:12,840 --> 00:06:14,400 they require higher levels of maintenance 179 00:06:14,400 --> 00:06:16,770 because they're using a gas-based engine. 180 00:06:16,770 --> 00:06:18,300 These generators are usually carried 181 00:06:18,300 --> 00:06:19,950 to the location where they're going to be needed. 182 00:06:19,950 --> 00:06:21,300 Then the device that requires power 183 00:06:21,300 --> 00:06:22,590 is going to be connected to the generator 184 00:06:22,590 --> 00:06:23,880 using an extension cord. 185 00:06:23,880 --> 00:06:25,980 And finally, the generator is manually started up 186 00:06:25,980 --> 00:06:27,870 and run to provide that power. 187 00:06:27,870 --> 00:06:29,190 So you're probably not going to be using 188 00:06:29,190 --> 00:06:31,530 a portable gas generator for a large server room, 189 00:06:31,530 --> 00:06:32,430 but you may be able 190 00:06:32,430 --> 00:06:34,230 to keep some specialized equipment up and running 191 00:06:34,230 --> 00:06:36,090 using one of these portable systems. 192 00:06:36,090 --> 00:06:37,320 These generators can be run 193 00:06:37,320 --> 00:06:39,810 for either a short period of time or a long period of time 194 00:06:39,810 --> 00:06:42,150 depending on how much fuel you have available. 195 00:06:42,150 --> 00:06:44,760 For example, I have a portable gas engine generator 196 00:06:44,760 --> 00:06:46,800 that I can use if I lose power to my home, 197 00:06:46,800 --> 00:06:47,760 and our small generator 198 00:06:47,760 --> 00:06:49,830 will use about five gallons of fuel per day 199 00:06:49,830 --> 00:06:51,450 in order to provide me with enough electricity 200 00:06:51,450 --> 00:06:53,820 to run most of my lighting and my refrigerator. 201 00:06:53,820 --> 00:06:56,730 But it isn't powerful enough to run my air conditioning unit 202 00:06:56,730 --> 00:06:59,100 with the smaller portable generator that I have. 203 00:06:59,100 --> 00:07:01,860 So if you have a larger workload power need, 204 00:07:01,860 --> 00:07:04,710 you can use a permanently installed generator instead. 205 00:07:04,710 --> 00:07:06,210 These permanently installed generators 206 00:07:06,210 --> 00:07:07,440 usually make up the backbone 207 00:07:07,440 --> 00:07:10,200 of your data center's emergency power architecture. 208 00:07:10,200 --> 00:07:11,760 These permanently installed generators 209 00:07:11,760 --> 00:07:13,740 rely on either diesel fuel, propane, 210 00:07:13,740 --> 00:07:15,870 or other types of natural gas to operate, 211 00:07:15,870 --> 00:07:17,700 and these generators tend to be very large 212 00:07:17,700 --> 00:07:19,380 and they can power an entire building 213 00:07:19,380 --> 00:07:21,120 during a complete power loss event 214 00:07:21,120 --> 00:07:23,880 for hours, days, or even weeks at a time 215 00:07:23,880 --> 00:07:25,560 depending on how much fuel your system has 216 00:07:25,560 --> 00:07:27,090 in its reserve tanks. 217 00:07:27,090 --> 00:07:28,500 These permanently installed generators 218 00:07:28,500 --> 00:07:29,490 are directly integrated 219 00:07:29,490 --> 00:07:31,260 into your data center's electrical setup, 220 00:07:31,260 --> 00:07:32,700 and they're designed to kick in automatically 221 00:07:32,700 --> 00:07:34,440 during a power loss event. 222 00:07:34,440 --> 00:07:35,730 Battery inverter generators 223 00:07:35,730 --> 00:07:37,680 are the third type of generator we have, 224 00:07:37,680 --> 00:07:40,410 and they usually rely on large lead-acid batteries, 225 00:07:40,410 --> 00:07:43,380 nickel-cadmium batteries, or lithium-ion batteries. 226 00:07:43,380 --> 00:07:45,930 These battery inverter generators tend to be quieter 227 00:07:45,930 --> 00:07:47,070 and require less maintenance 228 00:07:47,070 --> 00:07:49,110 than either the portable gas engine generator 229 00:07:49,110 --> 00:07:51,240 or a permanently installed diesel, propane, 230 00:07:51,240 --> 00:07:53,070 or natural gas generator. 231 00:07:53,070 --> 00:07:55,500 Unfortunately, most battery inverter generators 232 00:07:55,500 --> 00:07:57,090 can only provide minimum wattage 233 00:07:57,090 --> 00:07:59,220 or provide power for a short duration of time 234 00:07:59,220 --> 00:08:00,240 during an outage, 235 00:08:00,240 --> 00:08:02,400 so they aren't really designed for prolonged use. 236 00:08:02,400 --> 00:08:04,320 Instead, they're useful for bridging the gap 237 00:08:04,320 --> 00:08:06,330 until a longer-term backup solution, 238 00:08:06,330 --> 00:08:08,430 like the diesel generator, propane generator, 239 00:08:08,430 --> 00:08:10,920 or natural gas generator, can be brought online 240 00:08:10,920 --> 00:08:13,410 and take over our power supply needs. 241 00:08:13,410 --> 00:08:16,110 Fourth, we have power distribution centers. 242 00:08:16,110 --> 00:08:19,410 Now, a power distribution center, also known as a PDC, 243 00:08:19,410 --> 00:08:21,960 acts as a centralized hub where power is received 244 00:08:21,960 --> 00:08:23,670 and then distributed to all of your systems 245 00:08:23,670 --> 00:08:25,230 throughout your data center. 246 00:08:25,230 --> 00:08:26,640 A power distribution center 247 00:08:26,640 --> 00:08:28,680 is not just a massive power strip, though, 248 00:08:28,680 --> 00:08:30,750 because it consists of a sophisticated system 249 00:08:30,750 --> 00:08:32,760 that uses integrated circuit protection, 250 00:08:32,760 --> 00:08:34,350 monitoring, and load balancing 251 00:08:34,350 --> 00:08:35,700 to ensure even distribution 252 00:08:35,700 --> 00:08:38,070 without overloading any of your circuits. 253 00:08:38,070 --> 00:08:39,630 A PDC can also be integrated 254 00:08:39,630 --> 00:08:41,820 with large uninterruptable power supplies 255 00:08:41,820 --> 00:08:43,770 and large permanently installed generators 256 00:08:43,770 --> 00:08:46,650 to ensure a seamless transition to a backup power system 257 00:08:46,650 --> 00:08:48,810 any time you are experiencing a power event 258 00:08:48,810 --> 00:08:52,110 that creates a power loss event from your power grid. 259 00:08:52,110 --> 00:08:54,000 Now, in order to ensure you have solid power 260 00:08:54,000 --> 00:08:55,260 to all of your devices, 261 00:08:55,260 --> 00:08:56,670 you're going to need to build your data center 262 00:08:56,670 --> 00:08:59,340 with multiple layers of protections and redundancies. 263 00:08:59,340 --> 00:09:01,740 Your exact setup is going to be defined by your use case 264 00:09:01,740 --> 00:09:03,450 and your budgetary limitations, 265 00:09:03,450 --> 00:09:05,130 but most large data centers 266 00:09:05,130 --> 00:09:07,872 will use rack mounted uninterrupted power supplies 267 00:09:07,872 --> 00:09:09,090 to be able to provide line conditioning 268 00:09:09,090 --> 00:09:10,650 and battery backup functionality 269 00:09:10,650 --> 00:09:13,530 to all the servers contained within a given server rack. 270 00:09:13,530 --> 00:09:15,510 These batteries are usually going to be sufficient 271 00:09:15,510 --> 00:09:16,530 to maintain the power load 272 00:09:16,530 --> 00:09:18,270 for all the servers in a given rack 273 00:09:18,270 --> 00:09:20,190 for about 10 to 15 minutes. 274 00:09:20,190 --> 00:09:22,800 Your data center should also use power distribution units 275 00:09:22,800 --> 00:09:25,080 to perform line conditioning and load balancing 276 00:09:25,080 --> 00:09:28,020 to each server rack from your main utility power source, 277 00:09:28,020 --> 00:09:30,120 and in the case of a power loss event, 278 00:09:30,120 --> 00:09:31,380 the power distribution centers 279 00:09:31,380 --> 00:09:33,930 can also receive their power from backup generators 280 00:09:33,930 --> 00:09:36,660 if your grid power is lost or unavailable. 281 00:09:36,660 --> 00:09:39,270 These generators usually take about 30 to 60 seconds 282 00:09:39,270 --> 00:09:42,120 for them to start up, and then once they come up to speed, 283 00:09:42,120 --> 00:09:44,340 they'll be ready to start carrying the power load 284 00:09:44,340 --> 00:09:47,160 that you need to your power distribution centers. 285 00:09:47,160 --> 00:09:49,800 So remember, when it comes to powering your data centers 286 00:09:49,800 --> 00:09:52,590 and protecting them against surges, spikes, sags, 287 00:09:52,590 --> 00:09:55,260 undervoltage events, and complete power loss events, 288 00:09:55,260 --> 00:09:57,330 you can rely on the use of line conditioners, 289 00:09:57,330 --> 00:09:59,430 uninterruptible power supplies, generators, 290 00:09:59,430 --> 00:10:01,020 or power distribution centers 291 00:10:01,020 --> 00:10:03,600 to be able to service all of your various power loads. 292 00:10:03,600 --> 00:10:05,370 Line conditioners are devices designed 293 00:10:05,370 --> 00:10:06,690 to improve the quality of your power 294 00:10:06,690 --> 00:10:08,670 that's being delivered to your electrical load equipment 295 00:10:08,670 --> 00:10:11,640 by ensuring a stable voltage supply is being given. 296 00:10:11,640 --> 00:10:13,200 An uninterruptible power supply 297 00:10:13,200 --> 00:10:15,540 is a device that provides emergency power to a load 298 00:10:15,540 --> 00:10:18,180 when its normal input power source will fail. 299 00:10:18,180 --> 00:10:19,380 A generator is a machine 300 00:10:19,380 --> 00:10:21,960 that converts mechanical energy into electrical energy 301 00:10:21,960 --> 00:10:23,490 for use in an external circuit 302 00:10:23,490 --> 00:10:26,010 through the process of electromagnetic induction. 303 00:10:26,010 --> 00:10:28,650 And power distribution centers are specialized facilities 304 00:10:28,650 --> 00:10:30,900 that receive electrical power from a primary source 305 00:10:30,900 --> 00:10:33,450 and distribute it to one or more secondary circuits. 306 00:10:33,450 --> 00:10:35,640 By understanding their roles and the importance of each, 307 00:10:35,640 --> 00:10:38,700 we can better ensure that our digital systems remain online 308 00:10:38,700 --> 00:10:40,683 and operational at all times.