Summary: How to check 3 motor phase?

Article details

Summary of how to check the 3 phase motor whether it is good or bad, basic, like a real mechanic, easy to understand.

1️⃣ Visual check (Visual Check)
The motor is burnt / has a burning smell ❌
Wires, connectors, loose, cracked frame ❌
Rear fan broken / dust clogged ❌
👉 If you have these symptoms = high risk of loss.

2️⃣ Measure coil resistance (Ohm Test)
📟 Use a multimeter in Ω mode.
measure between
U–V
V–W
W–U
good value
The ohm value must be similar for both 3 pairs.
If any pair is “broken (∞)” or “abnormally low” → the coil is broken.

3️⃣ Check for electrical leaks to ground (Insulation Test)
📟 Use
measured from
U → Ground
V → Ground
W → Ground
The value you should get
greater than 1 MΩ (the higher the better)
Lower than 1 MΩ ❌ Risk of electrical leakage / shock.

4️⃣ Turn the shaft and check the bearings.
When you turn it, it must be smooth, not stiff.
No scraping/whining noise
❌ Friction = The ball bearing starts to fail.

5️⃣ Test power supply (Run Test)
⚠️ Must be safe.
The currents in both 3 phases must be similar.
There is no abnormal noise.
Doesn't vibrate too hard / doesn't heat up too quickly.
❌ High current in one phase = coil problem.

Short summary, easy to remember 🧠
🔍 See condition
📏 Ohm measurement
⚡ Check ground
🔄 Rotate the shaft
🔌 Test run