This video explains how to connect a Wye-Delta bank using three single-phase transformers with two primary bushings. It shows how to float the Wye point, connect delta secondaries, and identify lighter and power transformers. It also covers hazards of floating neutrals and how to reconfigure the bank as open-Wye open-Delta for temporary service.
Language: English
Transformer Selection
This video explains how to select the correct transformers for building a three-phase bank. It shows how to match system voltage, customer voltage, and KVA size from the work order to the nameplate, then check impedance and polarity for compatibility. It emphasizes using matched transformers to ensure balanced load and safe, reliable operation.
Secondary Coils
This video explains the difference between series and parallel secondary coil connections in single-phase transformers. It shows how series wiring provides 120/240 volts for delta systems and parallel wiring provides 120 volts for wye systems. It covers KVA impacts, tagging conventions, and the “alley cat, bad dog” method for safe, accurate coil pairing.
Phase-to-Phase or Phase-to-Ground Transformers
This video explains how a dual-rated transformer can connect either phase-to-phase or phase-to-ground. It shows how to interpret dual voltage nameplates, determine the correct connection based on system voltage, and recognize Y versus Delta configurations. It reinforces matching coil ratings to system voltage for safe, efficient transformer operation.
Phase-to-phase Only Transformers
This video explains transformers designed for phase-to-phase connections. It shows how to identify them by a single voltage rating and two primary bushings, meaning the same value serves as both system and coil voltage. It reinforces that connecting phase-to-phase ensures efficient operation and protects transformer life.
Phase-to-Ground Only Transformers
This video explains transformers designed for phase-to-ground connections only. It shows how to identify them by a single primary bushing and a nameplate marked with two voltage ratings and “GRDY,” meaning the neutral end must be grounded. It emphasizes correct grounding and voltage checks to ensure safe transformer operation.
Open Wye – Open Delta Banks
This video explains how to connect open-Y, open-delta banks using the same-opposite and opposite-same methods. It shows how each connection is wired on both the primary and secondary sides, identifies lighter and power transformers, and notes that both setups deliver the same voltage. It emphasizes choosing configurations based on field conditions and safe verification.
Open Delta – Open Delta Banks
This video explains how to connect an open-delta bank using two single-phase transformers to supply both single-phase and three-phase power. It shows how to wire the primary and secondary sides, designate lighter and power transformers, and ground the neutral. It notes open-delta banks operate at 57.7% efficiency compared to closed banks.
Open Banks
This video explains how open banks operate using two transformers instead of three to complete two-thirds of a Delta or Wye configuration. It shows how to connect open Delta and open Wye systems, when to use each, and how lighter and power transformers share single-phase and three-phase loads. It reinforces proper setup and voltage checks for safe operation.
Determining Secondary Connections
This video explains how open banks operate using two transformers instead of three. It demonstrates primary connections for open Delta and open Wye setups, showing how each functions and when to use them. It also explains lighter and power transformers, noting that open banks supplying three-phase power always use an open Delta secondary.