Open WyeWye 120208 4 wire This bank is

Open Wye-Wye 120/208 4 wire

This bank is used to supply a three phase four wire service of 120/208 volts when only two different phase wires are available. One of the transformers will need to be twice the KVA capacity as the others as it will have full line current on both coils. The tank straps connected to the smaller transformers X 2 bushings will need to be removed. One of the X 2’s will become a secondary phase wire. The other is removed to prevent secondary neutral current from flowing on the case grounding system. This connection is not a very efficient use of transformers but is useful in a temporary application or emergency.

OSHA Required Tailgate Discussion Topics • Hazards Associate with the job • Work Procedures Involved • Special Precautions • Energy Source Controls • PPE Required

Work Procedures Involved Hazards associated with the job Energy Source Controls Special Precautions Personal Protective Equipment A safe job begins with a thorough inspection of… Be sure to. Tools record your Be certain all of your tools emergency location Be andaware post in ofayour area, be sure to cover arework in good shape. location everyone on the crew anything you can reach touch or fall into. And knows. anything that can reach fall into Equipment Make suretouch youror trucks are you! all in Have your PPE and First Aid kit needed Discuss all PPE for the job and wear your working order take time to preflight available Be toofinspect your equipment prior to use. are your equipment and insure there Working in traffic exposes you to hazards that Slips trips and PPE. falls aresure some the Be sureare your AEDIdentify isto accessible. alllook voltages you are exposed surprise. difficult control. Give vehicles plentyto. Be sure to most common injuries, fornothe all of your protective gear on. time tohave see and avoid you! Follow the hazards of that could cause this. Be. Arc-Flash afor dedicated observer Line/Structure Look over line and structure. Are manual of wear traffic. Identify control yourthe area. sure to inspect and your fall there any potential hazards? (Broken arrest harness. insulators, damaged wire, clearances over roads or from trees? )

Hang the required hardware Note the side that has two cutouts is opposite the system neutral. You only need two cutouts.

Parallel two of the transformers internally. Leave one series internally. This transformer will need to be twice the KVA as the others. Ground all of the transformer cases as well as the transformer cluster.

Remove the tank strap from the X 2 bushing of the smaller left and center transformers. X 2 Remove tank strap

Connect all primary H 2 bushings together and then connect them to the system neutral. H 2

Connect all primary H 1 bushings of the center and left transformers to the left cutout. H 1

Connect all primary H 1 bushings of the right side transformers to the cutout. H 1

Connect the center transformers X 2 and the larger right hand transformers X 2 together and then to the service neutral. X 2 Neutral X 2

Connect the Larger right hand transformers X 3 to the far left transformers X 1. This wire should be isolated from everything else. X 3 X 1 Neutral

Connect one of the service lines to the left transformers ungrounded X 2 bushing. X 2 Neutral Line

Connect one of the service lines to the center transformers X 1 bushing. X 1 Neutral Line

Connect one of the service lines to the larger right hand transformers X 1 bushing. X 1 Neutral Line

With the cutouts open, connect the primary jumpers to different phases. Neutral Line

Close the cutouts, test voltage and rotation. Neutral Line