Surge Brownout Voltage Protector: How to determine if home appliances are damaged due to a broken neutral line
Date:2025-04-24 Click:37
This article, from the manufacturer of surge brownout voltage protectors, explains how to determine whether home appliances need to be replaced after they are damaged due to a broken neutral wire, helping you make a scientific decision on whether to repair or replace them.
1. Warning signs to stop using immediately
Please turn off the power immediately and consider replacing the appliance if you encounter the following situations:
Visible damage:
○ Scorch marks/melted plastic (such as blackened sockets, and melted wire sheaths).
○ Component explosion (such as capacitor bulging and explosion, circuit board carbonization).
Abnormal phenomena:
○ Continuous burning smell or smoke.
○ Internal sparks or explosions (such as "crackling" sounds inside the motor).
Safety test failure:
○Use a multimeter to detect that the outer shell is charged (voltage to ground > 36V).
○The leakage protector trips immediately after closing.
2. Judgment criteria by type
Electric heating appliances (electric kettles, electric heaters)
| Repairable condition | Replacement required |
| Fuse only blown | Heating tube deformation/breakage (resistance value deviation > 15%) |
| Switch contacts burned out (can be polished) | Thermostat metal sheet permanent deformation |
Typical case:
After the electric kettle is operated at 380V voltage, if the resistance of the heating tube changes from 32Ω to ∞ (open circuit) or <5Ω (short circuit), it must be replaced.
Electrical appliances (refrigerators, air conditioners, washing machines)
| Repairable conditions | Replacement required |
| Starting capacitor bulge (replace capacitor) | Motor winding short circuit (megohmmeter reading < 0.5MΩ) |
| Belt slippage (replace belt) | Compressor stuck (does not rotate at all after power is turned on) |
Professional testing method:
Use a clamp meter to measure the operating current. If it exceeds the rated value by 30% and is accompanied by severe vibration, it means that the motor is damaged and needs to be replaced.
Electronic appliances (TV, stereo)
| Repairable situation | Replacement required |
| Power board fuse burnt out (replace fuse) | Motherboard chip breakdown (such as main control IC overheating and cracking) |
| Individual capacitor failed (replace capacitor) | Vertical bright lines/color screen (panel damage) |
Cost reference:
The mainboard repair cost of a 32-inch LCD TV is about ￥200-400. If the cost of replacing the screen is greater than 60% of the new price, it is recommended to replace it.
Lighting equipment (LED lights, ceiling lights)
| Repairable condition | Replacement required |
| Drive power supply damaged (replace power supply) | Large area of LED lamp beads blackened (light decay > 70%) |
| Poor switch contact | Lamp housing deformed (heat dissipation failure risk) |
Repair value evaluation formula
Decision formula:
Repair cost + Remaining life loss ≥ New machine price × 0.6 → Replacement recommended
Calculation example:
A 5-year-old air conditioner has a repair cost of ￥800 and is expected to last for 2 years after repair:
Residual value: New machine ￥3000 × (2/8 years) = ￥750
Total expenditure: 800+750=￥1550 > 60% of new machine price (￥1800) → It can still be repaired, but if the repair cost exceeds ￥1200, it is recommended to replace it with a new one.
Safety reuse test process
Basic test:
○Measure insulation resistance (motor type>2MΩ, electric heating type>5MΩ).
○Run at no load for 30 minutes and monitor temperature rise (shell temperature ≤60℃).
Function verification:
○Refrigerator: -18℃ in freezer must be reached within 2 hours.
○Washing machine: dehydration speed deviation <10%.
Long-term observation:
○Check for odor within 24 hours after first use.
○Monitor power consumption weekly (compared with historical data)
Decision suggestions for different usage scenarios
| Scenes | Recommended solutions |
| Old appliances in rental houses | Direct replacement (high risk of legal disputes) |
| High-end imported appliances | Official repair first (keep the original motherboard) |
| Affordable appliances after warranty period | Replacement if the repair fee exceeds ￥300 |
| Backup/low-frequency appliances | Downgrade after repair (e.g. a repaired refrigerator is only used for beverage refrigeration) |
Recommendations for purchasing household appliances when replacing them and matching solutions for surge voltage protectors
1. Core principles for purchasing household appliances: surge protection and wide voltage design
Wide voltage input compatibility
Choose household appliances marked with a "wide voltage range" (such as 170-264V). Such devices have built-in voltage regulator modules to cope with short-term voltage fluctuations and reduce the risk of undervoltage or overvoltage. For example, high-end refrigerators and air conditioners often support wide voltage input.
2. Built-in surge protection design
Varistor (MOV) or transient suppression diode (TVS): Give priority to household appliances that are marked with such components, such as some smart TVs and routers, which can effectively absorb transient overvoltage.
3. Energy efficiency and safety certification
International certification: Prioritize products that have passed the anti-interference test to ensure that the equipment has self-protection capabilities when the voltage is abnormal.
Energy efficiency level: Class I energy-efficient equipment (such as air conditioners) usually has a more stable circuit design and higher long-term reliability.
Cooperative protection scheme for home appliances and surge protectors
Surge protectors (SPDs) are core devices to ensure the safety of home appliances and need to be configured in layers according to the power usage scenario and the characteristics of home appliances. The following is an optimization scheme based on the characteristics of surge protectors:
Protection scheme for high-power appliances (air conditioners, water heaters)
1. T2-level surge protectors
- Supports installation in branch distribution boxes, can withstand Imax=40kA (8/20μs waveform), residual voltage ≤1.5kV, and effectively suppresses the impact of grid fluctuations on core components such as compressors.
- Functional highlights: Built-in delayed restart function (3-5 minutes) to avoid coil overheating caused by frequent start-stop of the compressor at the moment of voltage recovery.
2. Voltage stabilizer assistance
- It is recommended to install a voltage stabilizer in old power grid areas, with an output voltage regulation accuracy of ±3%, suitable for high-power equipment such as air conditioners.
Maintenance and economic recommendations
1. Regular inspection and replacement- Status monitoring: Schneider iPRD1 series is equipped with red/white/green three-color indicator lights. The red light is always on, indicating that the module has failed and needs to be replaced.
- Life management: MOV type voltage protectors are recommended to be replaced every 2 years. The Yizao EPO series uses chain discharge technology, and the life span can reach 20 years.
2. Cost control strategy
- Layered cost: Main switch T1 level + branch T2 level + socket T3 level, covering the whole house protection.
- Maintenance decision: If the cost of home appliance maintenance is greater than 40% of the new machine price, it is recommended to replace it with a wide voltage design model.
