In modern power supply guarantee systems, UPS (Uninterruptible Power Supply) plays a vital role, providing stable and continuous power support for various critical equipment. Among them, "overload capacity" as a key parameter of UPS is of great significance for ensuring the normal operation of equipment and coping with sudden power demands.

I. Definition of Overload Capacity

Overload capacity specifically refers to the ability of a UPS to withstand loads exceeding its rated power for a short period of time. This capability is usually expressed in the form of "percentage of rated power + duration". For example, common markings such as "125% load can be maintained for 10 minutes, 150% load can be maintained for 1 minute".

This means that when the load instantly increases to 125% of the UPS's rated power, the UPS can supply power stably for 10 minutes; if the load further increases to 150%, it can maintain power supply for 1 minute. This ability to cope with excess loads in a short period of time is an important manifestation of UPS performance.

II. Important Roles of Overload Capacity

Coping with Sudden Loads

In practical applications, many devices will generate a current much higher than their rated power at the moment of startup, that is, the starting current. Taking motor-type loads as an example, their starting current can usually reach 5-7 times the rated current. At this time, if the overload capacity of the UPS is insufficient, the overload protection may be triggered when the equipment starts, resulting in the failure of the equipment to start normally, and thus affecting the operation of the entire system. A UPS with good overload capacity can provide additional power support in the short moment when the equipment starts, ensuring the smooth start of the equipment and maintaining the stable operation of the system.

Ensuring System Reliability

In some scenarios with high requirements for the stability of power supply, such as data centers, medical equipment, communication base stations, etc., any short-term power interruption may cause serious consequences. The overload capacity of the UPS can effectively cope with power overload caused by sudden situations such as equipment failure and instantaneous high load demand, prevent power supply interruption caused by overload, thus providing reliable power guarantee for key equipment and reducing the risk of system operation.

III. Applications of Overload Capacity in Different Scenarios

Industrial Production Field

In industrial production, large-scale equipment such as machine tools, cranes, and compressors will generate large current fluctuations during startup and operation. Industrial-grade UPS, with its excellent overload capacity (usually able to withstand 125%-150% of the rated load for a few seconds to a few minutes), can cope with equipment startup impact and overload demands under abnormal working conditions, ensuring production continuity. For example, the automated production line equipment in automobile manufacturing plants starts and stops frequently, and the overload capacity of the UPS can avoid production stagnation caused by power problems.

Data Centers

Servers, storage devices, etc. in data centers have high requirements for power stability. When server clusters start at the same time or perform large-scale data backup, the power demand will surge instantly. A UPS with strong overload capacity can provide sufficient power support to prevent data loss, equipment damage, or business interruption. For example, when a data center of an Internet company expands its equipment, the overload capacity of the UPS ensures the stable power supply during the equipment access and startup process.

Medical Industry

Equipment such as CT scanners, nuclear magnetic resonance instruments, and life support systems in hospitals do not allow any power outage. The overload capacity of the UPS can cope with overload demands during equipment startup, mode switching, or short-term failures, ensuring stable operation of the equipment. For example, precision equipment in the operating room has strict requirements on power stability, and the overload protection of the UPS can prevent surgical interruption caused by overload.

IV. How to Consider Overload Capacity When Selecting a UPS

Matching Load Starting Current

It is necessary to accurately evaluate the starting current characteristics of the load equipment. For equipment with large starting current such as motor-type and inductive loads, a UPS with sufficient overload capacity should be selected. For example, if the starting current of the load is 6 times the rated current, it is necessary to ensure that the UPS can withstand the load of the corresponding multiple of the rated power.

Considering Application Scenario Requirements

Different scenarios have different requirements for overload capacity:

• Scenarios with extremely high requirements for power stability, such as financial transaction centers and air traffic control systems, need to select UPS with strong overload capacity and high reliability;

• Ordinary office or home applications have lower requirements, but they also need to select UPS that can meet certain overload demands according to the load situation to cope with equipment increase or instantaneous overload.

Referring to Product Specifications and Actual Tests

When selecting, in addition to referring to the overload capacity indicators provided by the manufacturer, it is necessary to verify their authenticity through actual tests (there are false standards in the market). The test can simulate load startup, overload operation and other scenarios, and observe the output voltage stability and power supply duration of the UPS.

Combining with UPS Rated Power

Overload capacity is closely related to rated power: UPS with higher rated power has larger capacity of power device modules and stronger transient overload capacity. Therefore, when selecting, it is necessary to consider both rated power and transient overload capacity. For example, when starting a large motor, if the rated power of the UPS is too small, even if the overload index meets the standard, the startup may fail due to insufficient capacity of power devices.

V. Impact of Overload on UPS and Countermeasures

Impact

• Long-term overload will aggravate the heating of power devices inside the UPS, accelerate component aging, and even cause damage;

• If a UPS powered by a battery is overloaded, the battery discharge current will be too large, shortening the battery life and irreversibly reducing the battery life and charge-discharge performance.

Countermeasures

• In the system design and selection stage, reasonably evaluate the load demand and select a UPS with suitable overload capacity;

• Pay close attention to the load during daily use to avoid overloading. Some high-end UPS have intelligent monitoring functions, which can warn when approaching the overload threshold and remind users to adjust the load;

• Reasonably plan the scheduling of load equipment, such as avoiding simultaneous startup of multiple high-load equipment, to reduce the risk of instantaneous overload.

Summary

The overload capacity of UPS is a key parameter to measure its performance and applicability. In practical applications, fully understanding and rationally utilizing this capability is of great significance for ensuring stable operation of equipment, improving power reliability, and reducing system costs. Whether in industrial production, data centers, or medical fields, selecting a UPS with suitable overload capacity is an important part of building a reliable power guarantee system.