Relocating a Three Phase Transformer Bank WyeDelta 120240

Relocating a Three Phase Transformer Bank Wye/Delta 120/240 4 Wire Service. DISCLAIMER: This job hazard analysis (JHA) has been made available for informational and educational purposes only. The IAEC does not make any representation or warranty with respect to the accuracy, applicability, fitness, or completeness of the JHA. The IAEC hereby disclaims any and all liability to any party for any direct, indirect, implied, punitive, special, incidental or other consequential damages arising directly or indirectly from any use of this JHA which is provided as is.

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? )

Identify the Existing Connection 1. Label all secondary wires on the service side. 2. Identify voltages on the service side, particularly the “wild leg” if there is one. 3. Check the rotation on the secondary side and record it.

Identify the Existing Connection 1. This connection is a Wye Delta with the primary “Wye Point” floated (not connected to the neutral or ground) 2. Take a few digital pictures of the bank. 3. Identify what one of the quadraplex service wires are fed from each of the lines connected to the bank.

Identify the Existing Connection 1. Follow the service wires to identify what they are connected too. 2. Label them *Please note that the color code shown in the picture may not be correct it is shown as an example.

Identify the Existing Connection. Notice The left transformer is connected to the left phase. The center transformer is connected to the center phase. The right transformer is connected to the right phase. They are fed into the H 2 bushings and the H 1 bushings are tied together. Changing this to feed the H 1 and tying the H 2 bushings together will have no effect on rotation if you choose to.

Identify the Existing Connection. Notice The bank is a Wye/Delta 120/240 4 wire service. This bank will have two lighting legs ( 120 v to ground) and a “wild leg” with 208 v to ground. In the diagram it shows this with a blue identification. *Please note that the color code shown in the picture may not be correct, it is shown as an example.

Build the New Bank 1. It will be easy to just duplicate the bank as it was previously constructed. You can use your digital pictures for this.

Build the New Bank 1. Install the new URD service wires to the new bank. 2. If the wires have identification on them use of these will simplify to identification of the secondary lines. 3. If there are no markings you must ohm them out to identify them.

Build the New Bank 1. Identify the colors as they were on the old bank and connect them in the same positions as they were on the old bank. *Please note that the color code shown in the picture may not be correct, it is shown as an example.

De-Energize the Old Bank and Service 1. Have the member disconnect their load. 2. Temporarily bond the wye point with the use of a protective ground a hot stick. 3. Open the cut-outs.

Disconnect, test, and Ground the Primary Tap Lines.

Install the New Primary Line *Please note that the color code shown in the picture may not be correct, it is shown as an example.

Complete the Primary Connection *Please note that the color code shown in the picture may not be correct, it is shown as an example.

Install the new URD Service to the existing Service Pole. 1. These should already be identified by either previous markings or ohming them out. *Please note that the color code shown in the picture may not be correct, it is shown as an example.

Remove the Old Service and Install the New URD Service to the Existing Service Pole. 1. Follow the markings you have been using. *Please note that the color code shown in the picture may not be correct, it is shown as an example.

Remove Grounds and Re-energize the Primary Tap Lines.

Energize the New Bank. 1. 2. 3. Temporarily bond the wye point with a protective ground so it can be removed with a hot stick when energizing is completed. Close the cutouts. Remove the temporary wye point ground. *Please note that the color code shown in the picture may not be correct, it is shown as an example.

Test the New Service 1. Be certain all voltages are the same as they were prior to changing the bank. 2. Insure that the rotation is the same. 3. If the rotation is not correct change the lighting legs around and recheck everything. *Please note that the color code shown in the picture may not be correct, it is shown as an example.