1. Wye/Wye 277/480 4 wire Transformer Bank
© 2018 Iowa Association of Electric Cooperatives

2. OSHA Required Tailgate Discussion Topics
Hazards Associate with the job
Work Procedures Involved
Special Precautions
Energy Source Controls
PPE Required
The five topics required by OSHA to discuss in the tailgate.
First letter from each topic = How Well Should Everyone Plan
© 2018 Iowa Association of Electric Cooperatives

3. Hang the required hardware
Note the side that has two cutouts is opposite the system neutral.
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4. © 2018 Iowa Association of Electric Cooperatives

5. Parallel all of the transformers internally.
Ground all of the transformer cases as well as the transformer cluster.
© 2018 Iowa Association of Electric Cooperatives

6. © 2018 Iowa Association of Electric Cooperatives

7. Connect the primary jumpers
Connect the primary jumpers. Leaving the high side jumpers connected to the system neutral until the entire connection is completed. H1 H2
© 2018 Iowa Association of Electric Cooperatives

8. H1 H2
© 2018 Iowa Association of Electric Cooperatives

9. You may use single bushing transformers for this connection
Connect the H2 bushings together and connect them to the system neutral and ground.
You may use single bushing transformers for this connection
© 2018 Iowa Association of Electric Cooperatives

10. © 2018 Iowa Association of Electric Cooperatives

11. Connect this to the secondary neutral
Connect all X2’s together with a jumper of equal capacity to the secondary phase wires.
Connect this to the secondary neutral X2
Neutral
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12. X2
Neutral
© 2018 Iowa Association of Electric Cooperatives

13. Connect the secondary phase wires to the X1’s.
Neutral
Power
Power
Power
© 2018 Iowa Association of Electric Cooperatives

14. X1
Neutral
Power
Power
Power
© 2018 Iowa Association of Electric Cooperatives

15. Connect the primary jumpers and close the cutouts.X1
Neutral
Power
Power
Power
© 2018 Iowa Association of Electric Cooperatives

16. X1
Neutral
Power
Power
Power
© 2018 Iowa Association of Electric Cooperatives

17. Check the secondary voltage and rotation.X1
Neutral
Power
Power
Power
© 2018 Iowa Association of Electric Cooperatives

18. X1
Neutral
Power
Power
Power
© 2018 Iowa Association of Electric Cooperatives