FAQ

When selecting a UPS system, the up-front cost necessarily comes into question and this can lead organisations sometimes buying a lesser product at a lesser cost. However, it is essential to check the small print to ensure you have chosen a modular system that it really will do the job intended: protect the critical power of your datacentre with the highest level of availability.

Interestingly, with some of the higher quality UPS systems, cost savings are often realised over the long-term through increased efficiency, resulting in lower running costs and a lower overall total cost of ownership (TCO) so doing a full cost analysis is usually worth calculating.

So, as their primary goal, how can datacentres select a UPS to maximise availability? Essentially, there must be no potential single points of failure. Understanding the configuration and the definition of a modular system carefully, before the deal is done, is critical.

At the most basic level, a single standalone UPS unit that protects a critical load is known as an N system configuration. However, a standalone UPS lacks any resilience in the event that the unit develops a fault or is offline for preventative maintenance. Paralleling a second standalone UPS unit of the same rating, provides resilience and is known as an N+1 configuration.It would be possible parallel several standalone units together of an individual smaller rating to give the same philosophy.

Another definition of modular is a standalone UPS designed and manufactured in a modular format. The main component parts of rectifier, inverter and static switch are modular. If there is a problem with say the rectifier for example, it can be swapped easily. The challenge with this configuration is that if one component does fail the whole UPS functionality goes down with it. It may be a modular system, but its level of availability will not be reliable.

A better solution is what we term: a true modular UPS. This is where several individual UPS modules are contained within a frame. All the individual modules are UPS in their own right, all containing a rectifier, inverter and static switch and all operating online in parallel with each other. For example, six 50kW UPS modules may typically be contained within a single frame offering a resilient configuration of 300KWs N+1. If required, it takes moments (around 30 seconds) to ‘hot-swap’ a module while the rest of the modules continue to protect the critical load.

At no point does the system need to be transferred to maintenance bypass and hence on raw mains.

Some other modular systems include the rectifier and inverter within their modules, but the static switch is centralised and separate. This results in a potential single point of failure. It may only take a few moments to replace a separate static switch, but depending on location, getting to the site to replace it may take a maintenance engineer several hours. During that time the system cannot transfer to static bypass. With a true modular system, where the static switch is included in each module, the rest of the modules in the UPS frame continue to protect the load until it can be replaced. This increases the level of availability dramatically.

We have developed our latest generation true modular UPS system which offers power factory of more than 0.99, with low total cost of ownership (TCO) through its Maximum Efficiency Management (MEM) and low losses of energy. Our design team has been working with data centres for many years at the forefront of technological development.

1. High-frequency machine:

Using high-frequency switching technology, high-frequency switching elements are used to replace the UPS of power frequency transformers in rectifiers and inverters, commonly known as high-frequency machines. High-frequency machines are small in size and high in efficiency.

2.Power frequency machine:

UPS using power frequency transformer as rectifier and inverter components is commonly known as power frequency machine.

High frequency machine VS industrial frequency machine.

2-1: The high-frequency machine does not have an isolation transformer, and its output zero line has high-frequency current, which mainly comes from the harmonic interference of the mains grid, the pulsating current of the UPS rectifier and the high-frequency inverter, and the harmonic interference of the load. The interference voltage is not only high in value but also difficult to eliminate. However, the output zero-ground voltage of the power frequency machine is lower, and there is no high-frequency component, which is more important for the communication security of the computer network.

2-2: There is no transformer isolation for the output of the high-frequency machine. If the inverter power device is short-circuited, the high DC voltage on the DC bus(DCBUS) will be directly applied to the load, which is a safety hazard, but the power frequency machine does not exist. question.

2-3: The power frequency machine has strong anti-load impact ability.

1. The energy ratio is relatively high. With high storage energy density, it has reached 460-600Wh/kg, which is about 6-7 times that of lead -acid batteries;

2. The service life is long, and the service life can reach more than 6 years. The battery with lithium iron phosphate as the positive electrode is charged and discharged at 1C (100% DOD), and has a record of 10,000 times of use;

3. The rated voltage is high (the single working voltage is 3.7V or 3.2V), which is approximately equal to the series voltage of 3 nickel-cadmium or nickel-metal hydride rechargeable batteries, which is convenient to form a battery power pack;

4. With high power endurance, the lithium iron phosphate lithium ion battery used in electric vehicles can reach 15-30C charge and discharge capacity, which is convenient for high-intensity start-up acceleration;

5. The self-discharge rate is very low, which is one of the most prominent advantages of the battery. Currently, it can generally achieve less than 1%/month, which is less than 1/20 of the nickel-hydrogen battery;

6. Light weight, the weight is about 1/5-6 of the lead-acid product under the same volume;

7. Strong adaptability to high and low temperature, it can be used in the environment of -20°C--60°C, after the process is processed, it can be used in the environment of -45°C;

8. Green and environmental protection, no matter it is produced, used or scrapped, it does not contain or produce any toxic and harmful heavy metal elements and substances such as lead, mercury, cadmium, etc;

9. Production basically does not consume water, which is very beneficial to countries that lack water.

The battery is an important part of the UPS uninterruptible power supply system. Reasonable maintenance of the battery can reduce the decay speed of the battery, increase the service life of the battery, greatly reduce the frequency of battery replacement, and effectively save operating costs.

1.Maintaining a suitable ambient temperature can prolong the service life of the UPS battery

Generally speaking, the factor that affects the UPS uninterrupted battery is the ambient temperature. Generally, the best ambient temperature required by battery manufacturers is between 20-25°C. Although the increase in temperature has improved the discharge capacity of the battery, the price paid is that the life of the battery is greatly shortened. As indicated by the test outcomes, when the natural temperature is over 25°C, the life of UPS will be diminished significantly for every 10°C of increment. At present, the batteries used in UPS are generally maintenance-free sealed lead-acid batteries, and the design life is generally 5 years, which can only be achieved under the environment required by the battery manufacturer. If it fails to meet the specified environments requirements, its lite span will vary greatly. In addition, the increase of the ambient temperature will lead to the enhancement of the internal chemical activity of the battery, thereby generating a large amount of heat energy, which will in turn increase the temperature of the surrounding environment. This vicious circle will accelerate the shortening of the battery life.

2.Regularly charge and discharge UPS uninterrupted battery

The floating charge voltage and discharge voltage in the UPS power supply have been adjusted to the rated value at the factory, and the discharge current increases with the increase of the load. The load should be adjusted reasonably during use, such as controlling electronic equipment such as a computer the number of units used. Under normal circumstances, the load should not exceed 60% of the rated load of the UPS. Within this range, the discharge current of the battery will not be over-discharged.

Because the UPS is connected to the mains for a long time, in an environment with high power supply quality and few occurrences of mains power outages, the battery will be in a floating charge state for a long time, which will lead to a decrease in the activity of the mutual conversion of chemical energy and electrical energy in the battery over time, and accelerate aging. And shorten the service life. Therefore, it should be fully discharged once very 2-3 months, and the discharge time can be determined according to the capacity of the battery and the size of the load. After a full load discharge, recharge for more than 8 hours according to the regulations.

3.Timely replacement of waste/bad UPS uninterruptible power supply batteries

At present, the number of storage batteries equipped with large and medium-sized UPS power supplies ranges from 3 to 80, or even more. These single batteries are connected through a circuit to form a battery pack to meet the needs of UPS DC power supply. In the continuous operation and use of UPS, due to the difference in performance and quality, it is inevitable that the performance of individual batteries will decline, and the storage capacity will not meet the requirements and be damaged. When some/some batteries in the battery pack are damaged, maintenance personnel should check and test each battery to exclude damaged batteries. When replacing a new battery, you should try to buy the same type of battery from the same manufacturer, and it is forbidden to mix acid-proof batteries, sealed batteries, and batteries of different specifications.

The PWM solar controller adopts three charging modes of strong charge, balanced charge and floating charge.

Strong charge:

also called direct charge, is fast charge, when the battery voltage is low, with high current and relatively high voltage to charge the battery.

Balanced charging:

After the intensive charging is complete, the battery will stand for a period of time. When the voltage drops to a certain value, the battery will enter the balanced charging state to ensure uniform and consistent battery terminal voltage.

Floating charge:

After the equalization charge is complete,the battery also stands for a period of time. When the voltage drops to the maintenance voltage, the battery is in the floating charge stage, so that the battery can be kept in the charging state without overcharging.

MPPT solar controller adopts MPPT limited current charging, constant voltage equalization charging and constant voltage floating charging mode.

MPPT limited current charging:

in the battery voltage is very small, the use of MPPT charging mode, the output power of the solar panel pumped to the battery end, the light intensity is very strong the output power of the solar panel increases, the charging current reaches the threshold, the TERMINATION of MPPT charging into constant current charging;

When the light intensity becomes weak, it will turn to MPPT charging mode.

Constant voltage charging:

the battery in MPPT charging mode and constant current charging mode free switch, cooperate with each other so that the battery voltage reached the saturation voltage, it entered the constant voltage charging stage, with the battery charging current gradual decreased to 0.01c, the charging stage terminated, into the floating charge stage.

Constant voltage floating charge:

the battery is charged with a voltage slightly lower than the constant voltage.

This stage is mainly used to supplement the energy consumed by the battery self-discharge.

Principle of inverter soft start:

1.Inverter soft start means that the voltage is gradually increased from zero to the rated voltage, so that there is no impact torque in the whole process of starting the motor, but a smooth start-up operation.

2.The soft starter is a novel motor control device that integrates motor soft start, soft stop, and multiple protection functions. Its main composition is a three-phase parallel thyristor and its electronic control circuit connected in series between the power supply and the controlled motor. Use different methods to control the conduction angle of the three-phase inverted parallel thyristor, so that the input voltage of the controlled motor changes according to different requirements, and different functions can be realized.

The function of the inverter soft start function:

1.At the moment when the inverter is powered on, the inverter is powered, but there will be a delay of about 2 seconds when outputting 220V. The voltage will not reach 220V immediately, but will slowly rise from 100V to 220V, yes. Protection of the inverter itself.

2.For example, a normal inverter with 1000W power will output 1000W when the inverter is powered on. If it is a soft start, the output will continue to rise, 700W-800W-900W-1000W.