How to design a 3-phase resistive load bank?

Question

We are trying to design a 3-phase resitive load bank to test some step up transformers. We are receiving 3-phase 208v and stepping up to 3-phase 600V with 3-step up transformers wired in delta. Its a floating system Each step up transformer is capable of 800VA.

Q. How do you wire up the load with resistors, to test each transformer at full load? A picture or diagram would be helpful.

Answer 1

^{simulate this circuit – Schematic created using CircuitLab}

Figure 1. Delta transformer with delta load.

Each step up transformer is capable of 800 VA [at 600 V].

• From \$ P = \frac {V^2}{R} \$ we get \$ R = \frac {V^2}{P} = \frac {600^2}{800} = 450 \ \Omega \$.

If possible, having some way to test with load imbalance would be helpful.

450 Ω is your minimum on any phase. You can use any load between 450 Ω to infinity (open-circuit) on each phase.