How to Install a UPS (Uninterruptible Power Supply)
Power Distribution Requirements: The input and output wiring for the UPS should be prepared by a qualified electrician before the UPS arrives. Ensure the wires are pulled to the installation site with an extra length of 1 to 1.5 meters to facilitate smooth installation.
Wire Diameter Selection: The input and output wire diameters must comply with national electrical safety standards. For three-phase input and single-phase output systems, the bypass live wire and neutral wire must be three times thicker than the other live wires.
Wiring Guidelines: Use multi-core flexible copper wires for easier installation. Underground wiring should be sheathed in metal to protect against damage, including rat bites and electrical interference. Metal sheathing also shields electromagnetic interference, which is beneficial for communication signal lines.
Output Safety: The UPS output should be wired separately, and its dedicated sockets should be clearly distinguished from everyday power outlets with visible labels. UPS outputs should not be placed near or stacked with ordinary sockets to prevent accidental use by equipment like drills or vacuum cleaners, which can damage the power supply. The UPS is designed for weak inductive loads like computers and should not be used with strong inductive loads like printers or copiers unless the UPS has a power matching ratio of at least 4:1 for such devices.
Safety Grounding: Verify that the grounding resistance complies with national standards for safe operation and lightning protection. Install a circuit breaker in the power distribution cabinet to protect the input to the UPS. The breaker should have a slightly higher rating than the maximum input current to prevent frequent tripping.
Balanced Power Consumption: Ensure that the three-phase power in the distribution box is balanced to prevent issues like high zero-to-ground voltage, which can lead to unsafe operation or even fire hazards.
Operating Environment: The UPS should not be placed in humid or dirty areas without ventilation. Small UPS units should not be placed directly on the ground; use padding to prevent condensation. Medium and large UPS systems should ideally be placed in a dedicated server room, where the environment (dust, temperature, and humidity) can be controlled. Every 10°C increase in ambient temperature above 25°C halves the lifespan of the UPS battery.
Ventilation and Load-Bearing Safety: Leave at least 30 cm of space between the UPS and the wall to ensure proper ventilation. For medium and large UPS systems with extended battery life, ensure the floor can support the weight (maximum 1,000 kg per square meter for office buildings and 1,400 kg per square meter for industrial plants).
Lightning Protection: For UPS installations in rural or open areas, consider installing a high-power lightning protection device to prevent damage from lightning strikes, especially if the power is supplied via overhead lines.
Pre-Installation Inspection: Before installation, open the machine to inspect circuit boards, cables, capacitors, fuses, and mechanical parts to ensure they are secure and undamaged. If lighting is inadequate, use a flashlight for thorough inspection.
UPS Installation Precautions
- Input Power Stability: The user’s input power should fluctuate less than the UPS’s nominal mains fluctuation range. For example, if the UPS allows a fluctuation of ±20% at 220V, aim for ±15% to ensure smooth operation. The neutral-to-ground voltage should be less than 1.5V without load and less than 2V with full load.
- Avoid Leakage Protection: The UPS input and load circuits should not be equipped with circuit breakers that have leakage protection. The UPS connects the neutral and live wires to ground, creating a small current between them, which may trip the leakage protection.
- Neutral Line Connections: The UPS output neutral line (load) should not be connected to the input neutral busbar. For some UPS models, the input and output neutral lines are isolated, and connecting them could lead to interference. Ensure proper isolation of the neutral lines unless the UPS manufacturer specifies otherwise.
- Avoid Additional Equipment on UPS Input Breaker: Do not connect any additional electrical equipment to the lower port of the UPS input circuit breaker. The breaker is designed to control only the UPS input power.
- Circuit Breaker Ratings: Choose a circuit breaker with a rated voltage matching the input and output of the UPS. For single-input single-output UPS systems, use a breaker rated for 220V or 250V. For three-phase systems, use a breaker rated for 380V or 415V. The breaking capacity should meet the UPS manufacturer’s recommendations.
- External Battery Connection: The connection between the UPS and an external long-delay battery should be short to minimize voltage drop. Placing the battery near the UPS can also help maintain a stable operating environment.
- Separate Switchboard: It is recommended to install a separate switchboard for the UPS and its loads for centralized and reliable control. Ensure that the switchboard complies with national safety standards.