POTENTIAL FOR CATASTROPHE
Three hot-phase wires plus water. What could go wrong?
Often, consumers prefer that only the three hot phases of a 4-wire wye transformer bank or ungrounded delta circuit be brought out to the middle of a field to power a 3-phase pump motor for a center-pivot irrigation system. Most often, however, irrigation or load management control requires 120 or 240 volts. A common solution has been to derive operating voltage for control systems by using a conventional step-down transformer between phases or between a hot phase and a ground. (See Fig. A.) Since there is not a solid connection to the grounded bushing at the power transformer bank if the step-down transformer is connected from a hot phase and ground (not so with ungrounded delta), the ground itself is carrying the return current; certainly not a sound practice. In addition, conventional step-down transformers are prone to failure from lightning in addition to being difficult to mount.
TSTM feels that this is unpredictable, unstable, prone to expensive failure and, ultimately, a potentially dangerous risk to utilities, irrigation contractors, farmers and their families.
The solution is TSTM’s PowerPuckTM toroidal autotransformer. This flexible epoxy-sealed, weatherproof auto-transformer provides clean, reliable power at 240 and 120 V, protecting irrigation users and service workers from hot commons carrying phase-differential current, and deflecting power surges from control circuitry. (See Fig. B.)
This weatherproof, sealed unit is quickly and easily installed and can be mounted outside a cabinet through a knock-out if necessary, and can serve many different applications where reliable, safe low voltage power is needed. The plus is added protection for the downstream gear.
Quit using phase-derived low voltage. The cost-effective solution to protect equipment and people is TSTM’s PowerPuckTM. (See Fig. C.) Order one and give it a try at no risk today.