Document QgnnkRn7DjNG4YKeGvwZkO13o

I oorty planning --key to a modern system i*>& 'M Cheek possibilities for economical genoration: Total-Up plant joc**-h*al n#*ds a* a yardstick. la low-cosi or by product fust available? II generation le Indlealod. what six* units? How many? In planning layout. r*m#mbr modern designs sav* basement apace by bank* Ing cooling equipment alongside unit. Decide early on ownerehip and location, lower rate often goes with ownership but don't lorgel ttxed charges, mainte nance. Reliability of today's transform ers fgstljles using one 3-phase rather than 3 single-phase units. Whei utility leeds come In over long overhead linos, check lightning protection at substation. Can utility supply plant's demands eco nomically? Strive (or several leeds com ing (ram separate sources. What volt ages are available? Agree on switching procedure to keep plant operating la emergency. Captain working schedule lo utility so they can handle their main tenance without interrupting your Utd. . -. andfinish your planningjob by making decisions about supply today's spread-out one-story plants, substations on (he roof work well. There they can be reached easily by primary feeders. Or. consider putting (hem on balconies, up out of work zones. chase or generate? For some /actors to be checked, see pp 80, 81. Here aro some points to consider in planning (or either plant generation or utility supply. Oil-filled transformers are still first choice for Supply plans finish the job outdoor primary substations. Indoors, shift is away from vaults (o askarel or dry type. Look into sealed To select size and number of generating units, check dry-type where dust, moisture are problems. your maintenance-shutdown schedule, which critical Primary Feeds. Choice lor carrying them through loads must be carried and which may be dropped, the plant bolls down to overhead vs underground. Underground is oul of the way, unaffected by weather. But overhead offers lower initial cost, can be expanded readily. Keep feeders out of voluablo how much load, 11 any can be shifted to the utility, starting kva of large motors. Gan a power-inter change contract be worked out with the utility? If you plan to purchase, check your utility's ability work space--overhead trusses form good supports. Circuit Protection. A real must here Is a knowledge lo supply your load; power supply remains Ughl in some areas. And be sure utility knows what your of possible short-circuit currents. If you're lod from a utility, have them supply values at primary sub station. From that point on you oan determine what values will be at any point on your system. With voltage, hp ratings of load, and possible demands, load swings and load factor will be. Utility Feeds. For critical loads, study utility's system for supply reliability. If only a single line serves you. it may pay to bring in an additional one. Check voltage regulation. Starting large motors may be a short-circuit values, you have basic data to select problem if your plant is at end ol a long line. Vo)logo switchgear. For primary substations, give thought to economics and advantages of both circuit break ers and 1oad-inlerrtipler fused switches. regulators on utility line or load-ratio control on transformers help hold voltage up. For many plants, parallel operation with a utility Now you've worked your way back to the begin ning of the system--power supply. Big question: Pur is a good bet if it can be arranged. Consider value of provisions for quick disconnection if lightning i* a problem and continuous processes aro involved. IOOATI UCCTUCAl PCACtICC fOWM setting up your plant's power supply S! * Generation. Relate generaling-unit and food characteristics |o determine number and size. In selecting generator itself, con sider short-circuit ratio, cooling, regulation and voltage level. is. 1 Utility Feed. First work out details of primary substation ownership, number of feeders, voltage, etc Packaged equipment usually proves most economical. Check voltage-regulation needs. * Protection. How overcurrent relays with voltage restraint can tell faults irom permissible overloads. Transformer at pri mary substation should be guarded against surges and overloads. "-I