Introduction

As the energy core of modern electronic equipment, the safety, stability, and reliability of switching power supplies are directly related to the normal operation of the entire system. To give full play to the performance of switching power supplies and eliminate potential safety hazards, systematic standardized guidance is crucial. This paper aims to systematically elaborate on the safety key points and precautions for switching power supplies throughout their entire life cycle, including selection, installation, operation, and maintenance. Adhering to this specification is the fundamental prerequisite for ensuring that equipment receives a stable and clean energy supply, as well as achieving long-term, reliable, and safe operation.

I. Selection and Installation

1. Power Planning

Continuous Power: The rated power of the power supply should be 20%–30% higher than the maximum continuous power consumption of the equipment system to avoid long-term full-load operation.

Peak Power: If the load equipment has instantaneous peak currents (e.g., motor startup, large-capacity capacitor charging), the power supply must be selected to withstand such peak power, preventing protective shutdown caused by instantaneous overload.

2. Environmental Requirements

Safe Environment: Install the power supply in a dry environment without condensation, corrosive substances, or flammable/explosive gases. Special attention should be paid to non-waterproof power supplies.

Heat Dissipation and Ventilation: Ensure a heat dissipation space of more than 10 cm around the power supply. Never cover the ventilation holes or block the cooling fan to maintain smooth air circulation.

Temperature Derating: Higher ambient temperatures will reduce the output power of the power supply. When using the power supply in high-temperature environments, refer to the "derating curve" in the product manual and reduce the load accordingly.

3. Electrical Connection

Input Side: Confirm that the local power grid voltage falls within the rated input voltage range of the power supply (e.g., 85–264V AC).

Reliable Connection: All input and output terminal connections must be firm and reliable to prevent arcing, high temperatures, and fire hazards caused by loose connections.

Output Side: The wire gauge of the output wire must meet the requirements of the maximum output current to avoid overheating of the wire. For DC output, the positive (+) and negative (-) polarities must be clearly distinguished—reversing the polarity may damage the load equipment.

Reliable Grounding: The grounding terminal (PE) of the power supply must be reliably connected to the earth. This is a fundamental guarantee for preventing electric shock and a necessary measure to suppress electromagnetic interference.

II. Safe Operation

1. Confirmation Before Power-On

Before connecting the input power supply, be sure to recheck that the wiring (especially the output polarity and grounding) is correct.

2. Operating Status

No-Load Operation: Most switching power supplies allow no-load operation. Only some specially designed power supplies (e.g., certain high-power constant current sources) have minimum load requirements—always refer to the product manual for details.

Short-Circuit Protection: Although qualified power supplies are equipped with short-circuit protection functions, repeated or long-term output short circuits can still cause impact and cumulative damage to internal components, which should be strictly avoided.

3. High-Voltage Hazard Warning

Prohibition of Live Operation: Under power-on conditions, it is strictly forbidden to touch the interior of the power supply or adjust the wiring in any way.

Risk After Power-Off: After disconnecting the input power supply, the large-capacity filter capacitors inside the power supply may still store lethal high voltage, which can persist for several minutes or even longer.

Professional Maintenance: Non-professionals are strictly prohibited from disassembling the power supply by themselves. Maintenance work must be carried out by professionals after taking effective discharge measures and confirming that the capacitors are fully discharged.

III. Maintenance

1. Regular Cleaning

Regularly (recommended quarterly or according to environmental conditions) use a brush or compressed air (cold air) to remove dust from the inside and outside of the power supply. Ensure the power supply is completely disconnected before operation.

2. Regular Inspection

Regular inspection items should include: whether the output voltage is stable and normal; whether all wiring terminals are loose, ablated, or oxidized; and whether the housing is deformed, cracked, or abnormally heated.

3. Abnormal Handling

If the power supply emits a burnt smell, smokes, makes abnormal noises (e.g., popping sounds, continuous whistling), or overheats severely, the input power supply must be cut off immediately.

Do not power on the power supply again until the cause of the fault is clearly identified and completely eliminated; instead, have it inspected, repaired, or replaced by professionals.

Strictly adhering to this specification is the key to ensuring the safe and stable operation of switching power supplies and extending their service life.