# How to design a 3-phase resistive load bank?

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.

• Is your resistor bank intended to be used for load imbalance simulation? – Andy aka Jul 27 '18 at 16:03
• If possible, having some way to test with load imbalance would be helpful. – Douglas Jul 27 '18 at 16:06

## 1 Answer

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.

• He's using 1 800VA transformer per phase and you changed a 267 into a 167. At any rate, he's got 800VA per phase at 600V, so he wants to be able to test 600V@1.333A RMS per phase. That gives 450 ohms per phase and a power rating of ~1000-2000 W per phase. – K H Jul 28 '18 at 5:08
• Yup. Speed reading late at night is risky. Thank you. How did you calculate 1000 - 2000 W per phase? – Transistor Jul 28 '18 at 7:29