The use and maintenance of uninterruptible power supply system in modern large comprehensive hospitals

Generally speaking, a complete UPS power system mainly consists of six parts: monitoring system, power distribution system, air conditioning system, UPS host, battery pack, and load. As the operator and manager of the hospital logistics UPS, you should regard it as a system power supply network when using and maintaining it, rather than just focusing on the UPS host itself, so that you can better manage it and effectively solve fault problems.

Use and maintenance of UPS

1.Daily inspection

Daily inspection is to conduct regular inspections on the configuration, operation and working status of each part of the UPS. Through daily inspections and records, the operation and management personnel can grasp the operation and use of the equipment at any time, find out the hidden troubles of the UPS, and take timely measures to eliminate them. The operation and management personnel should formulate a scientific and detailed inspection item list, and check one by one according to the inspection items listed in the table during the inspection process to prevent missed inspections and mis-inspections. Daily inspection records should be bound into books and archived regularly for easy reference in the future.

Daily inspections can be implemented by “looking, smelling, listening, measuring, and doing”. Look: First, check whether the voltage, current and frequency of the AC input and output, and the values of the voltage and current of the DC input and output are normal; second, check the working status of each indicator light of the UPS; third, check whether the cooling fan is running normally; fourth, check whether the temperature rise of various heat-prone objects is too high. Smell: Mainly smell the position of the UPS fan outlet, all the connection lines of the UPS, and whether the battery pack has abnormal smells such as burnt smell. Listen: Listen for abnormal sounds. Different parts of the UPS will make different sounds during operation. The operating management personnel need to listen to the changes in normal and abnormal sounds based on experience to judge the operating status of the equipment. Measure: Whether the terminal voltage of the battery is normal, the temperature and humidity of the working environment, and the working temperature of the main heating components such as transformers, reactors, and power components. Do: Do some simple inspections, such as whether the indicator lights are intact and whether the fan is running normally. After the inspection, do all the record work.

The frequency of routine inspections can be determined based on specific requirements, or based on the actual service life of the UPS equipment, working environment, and climate changes.

2. Regular maintenance

After the UPS has been running for a period of time, it is necessary to carry out regular maintenance. During the regular maintenance process, problems can be found in a targeted manner through daily operation and inspection records; new problems can also be found comprehensively and carefully during regular maintenance to eliminate potential faults, so as to facilitate the stable operation of the equipment in the future. After completing the treatment of existing faults or potential faults, the operation and management personnel should also do the following work:

(1) Check whether the electrical connection screws are loose, whether the connectors are in good contact, whether the parts are damaged or scratched, and whether the wires are broken or broken.

(2) Check whether the components on the printed board have any color changes, whether the printed strips are peeling or scratched, and whether the solder joints have any cold solder joints, etc.

(3) Check for signs of yellowing, scorching or smoky areas, and for any capacitor explosion, damage, failure or deterioration.

(4) Check the wear of switches, contactors, etc., and whether the contact points are in good condition.

(5) Check whether there are any battery cells with lagging voltage and internal resistance in the battery pack.

(6) Check whether the insulation performance of the equipment is normal.

(7) Clean the equipment and remove dirt. If necessary, remove dust from the inside of the UPS host.

After finishing, turn on the machine to observe the operation and make regular records. After the regular maintenance is completed, be sure to carefully sort out the regular maintenance records, bind them into a book, and file them for future reference.

3. Precautions in operation, use and maintenance

As mentioned in the preface, operation managers need to look at daily inspection and maintenance work systematically, so they should also pay attention to the following matters:

(1) The actual load that the UPS can carry is related to the power factor of the load. When the load is purely resistive or purely inductive, its actual allowable output power is less than its nominal output power.

(2) The output end of the UPS should not carry inductive loads, thyristor-type and half-wave rectifier loads, such as compressors in refrigeration equipment used in hospitals. If such loads are required in actual work, it is necessary to increase the rated output power of the UPS, increase or change the ratio between the resistive load and the inductive load in the load, or directly add an isolation transformer and input and output filter devices between the UPS output end and the load.

(3) The input end of the backup UPS should not be equipped with an AC voltage stabilizer with large reactance components, because it will prolong the conversion time between the mains power supply and the inverter power supply. If an online UPS adds an AC voltage stabilizer at the front stage, it can ensure that the mains bypass power supply and the inverter power supply are in the same phase, frequency, and amplitude when performing the conversion, so that the switch is safe and successful. This is also a big difference between the online UPS and the backup UPS.

(4) When the UPS is working with load, if the UPS is used as a switch to directly turn it on and off, it is easy to burn out the power switch components of the inverter. Therefore, when it is necessary to turn the UPS on and off, it should be operated under no-load conditions as much as possible, and the number of unnecessary on/off operations should be reduced as much as possible to reduce the occurrence rate of human-caused failures.

(5) When the backup UPS is powered by AC power, its control circuit does not have the automatic fast protection function for overcurrent or short circuit. Therefore , the AC power input fuse capacity should not be easily increased.

(6) Online UPS should not be operated under heavy load when the battery bank connection switch is disconnected or the internal resistance of the battery bank becomes larger. This is because low-frequency interference and variable-frequency interference with the same frequency as the pulse width modulation wave will be generated on the DC input bus of the inverter. In severe cases, the interference will cause the inverter to operate, thereby causing a fault.

(7) If it is necessary to use a generator, the generator should be configured at least twice the rated capacity of the UPS, generally 5 to 10 times is the best.

(8) In addition, it is necessary to regularly check the environmental sanitation conditions, whether the UPS grounding circuit is in good condition, whether the air conditioning system is working properly, and the implementation of safety and fire protection measures in the equipment room.