If a machine or motor burnt because of high voltage, switch it off at the main, do not restart it, and have the voltage on every phase and the neutral checked before anything goes back on. Then get the motor rewound or the board repaired, and fit a stabilizer with high- and low-voltage cutoff — and phase-failure protection on a three-phase supply — so the next swing is corrected or cut off before it reaches the machine.
What should I do right now?
- Switch off at the main breaker. Do not keep trying to start the machine — each try can do more damage.
- Do not reconnect other equipment to the same supply until it has been checked. If one machine burnt, the fault may still be there.
- Take photos of the nameplate, the burnt part, the panel and any meter reading. You will need them for repair, warranty and choosing protection.
- Call a qualified electrician to measure voltage on each phase (phase to neutral and phase to phase) and check the neutral and earth.
- Write down what happened — the time, whether lights went very bright or dim, and whether the electricity had just come back after load-shedding.
Was it really high voltage?
Often, but not always. It matters, because the protection is different.
- High voltage mostly burns electronics: control boards, VFDs, chargers, LED drivers. It also overheats motor windings.
- Low voltage burns motors too. When voltage drops, a motor pulls more current to do the same work, and the winding heats up. So a "burnt motor" can be low-voltage damage, not high-voltage.
- A missing phase (single-phasing) on a three-phase motor makes it hum, overheat and burn quickly.
- A broken or loose neutral can push one single-phase line far above 250V while another drops low. This is a common cause of many appliances burning at once.
Machine kyun jal gayi — how do I find the cause?
Ask the rewinding shop how the winding burnt: one phase burnt usually points to a missing phase; all windings evenly burnt points to overload or long low voltage. Ask your electrician to check the neutral and earthing. If several appliances burnt at the same moment, suspect the neutral or a supply-side fault and report it to your electricity company.
How do I stop it happening again?
Fit protection that matches the cause:
- A stabilizer holds the voltage steady when supply swings, and cuts the load off if voltage goes beyond what it can correct. Look for high/low-voltage cutoff, a time delay on restart (so motors do not restart the instant power returns), and overload protection.
- On three-phase: a stabilizer with phase-failure protection. The Voltec SJW 3-phase units include over/under-voltage, phase failure, time delay, a digital volt/amp meter and a bypass switch. See three-phase industrial stabilizers.
- For sensitive single-phase machines (CNC controllers, lasers, medical devices), a solid-state stabilizer reacts faster than a servo: SCR in about 20 ms, IGBT 0 ms rated. More: stabilizers for laser, CNC and medical equipment.
What will a stabilizer NOT protect against?
Be clear on this before you spend money. A stabilizer is not a lightning arrester — a direct strike or large surge needs a surge protection device and good earthing. It does not fix a motor that is overloaded, jammed or has worn bearings. And it does not fix a bad neutral in your building: that must be repaired by an electrician. If your problem is one of these, we will tell you.
What size stabilizer does the machine need?
Read the kW or kVA and the voltage on the nameplate, add a 25% margin, and allow for the starting surge of motors. A compressor or motor can pull several times its running load for a few seconds at start. Single-phase or three-phase must match your supply. Step-by-step sizing for larger loads is in which stabilizer for a 50 kVA factory.