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A typical data center power supply system consists of equipment such as medium-voltage power distribution, transformers, low-voltage power distribution, uninterruptible power supply, terminal power distribution, and generators. Among them, the main role of UPS is to ensure that the load with it is continuously supplied before the mains power supply is interrupted and the generator is started.
The reliability of the UPS system directly affects the reliability of the data center, and at the same time, in the vast majority of data centers, the loss of the UPS system can account for more than 10% of the energy consumption of IT equipment. Understanding UPS is an important part of computer room construction.
In this article, we'll take a closer look at the top four common UPS questions:
1. UPS's brand selection
2. Power distribution calculation of UPS
3. Installation of UPS
4. Six major fault handling of UPS
First, the brand of UPS
There are many large and small brands of UPS uninterruptible power supply, and we usually use more in the project, mainly the following brands (in no particular order).
Among them, Shante, Emerson, Kehua, Crestec and other brands we often see in projects. Of course, in addition to the above brands, power source, Renda, Baoxing, etc. are also good, and they can be used according to the situation in actual projects.
2. UPS configuration calculation
For the formula calculation of UPS, we have mentioned before, it is more complicated to calculate, and many people do not understand, so today we will learn about the simple calculation method.
When used, it is calculated according to the following formula:
Required battery capacity (Ah) = UPS capacity (KVA) × 109 (Ah. blocks) / KVA / number of cells per group
Example 1:
For example, for the algorithm of designing UPS battery capacity of 109 Ah•block/kVA, a 120kVA UPS, with 32 batteries per group, requires a backup time of 60 min (i.e. 1h).
Then the required battery capacity is (60min):
120kVA×109Ah•块/kVA=13080Ah•块,
13080Ah•块/32块=409(Ah),
You can choose 4 sets of 12V, 100Ah batteries (32 pieces/group).
Note: The actual backup time is not enough to be close to 60min.
If there are 33 batteries per group, then 13080/33=396Ah, 4 sets of 12V and 100Ah batteries (33 pieces/group) can also be selected.
Note: The actual backup time of 33 blocks/group is more than 60min (one point exceeded).
If the backup time is required to be 30 minutes:
rule
109×120=13080Ah•块
13080/32=409Ah，
409/2=205Ah。
Since the discharge power and discharge time of the battery are not linear, that is, they cannot be simply divided by 2, but also multiplied by the correction factor. See Table 1 below, so 205×1.23=252Ah. You can choose 4 sets of 12V, 65Ah batteries (32 pieces/group).
Note: The actual backup time is more than 30min (more than one point).
If a backup time of 20 minutes is required:
Then 409/3=136Ah, but also need to be multiplied by the correction factor, see Table 1,136×1.41=192Ah, you can choose 12V, 65Ah battery 3 groups (32 pieces/group).
Note: The actual backup time is more than 20min (one point exceeded).
In other cases, and so on.
Example 2:
For the algorithm of 126Ah•block/kVA battery capacity, a 120kVA UPS, 32 cells per group,
If the calculation time is more than one hour, it should be divided by a correction factor after the above calculation, as shown in the table below.
The calculation method and multiplication correction factor are exactly the same as those described above.
For example:
The fallback time for the preceding example is 3 hours:
then 126×120=15120Ah•block,
15120/32=472Ah，
472×3=1417Ah；
It is also necessary to divide a correction factor, 1417/1.25=1131Ah.
It is necessary to configure 4 sets of 12V, 300Ah batteries (32 pieces/group).
According to the principle of conservation of energy, the above method is the same for three-phase/single-phase or single-phase/single-phase UPS.
Generally, each group of batteries equipped with medium and high-power UPS is 32; It is best not to exceed 4 groups of batteries in parallel, so as not to affect the current sharing and charging effect of the battery pack.
The above is a quick estimate and not particularly precise. However, it can be used as a reference, in order to get accurate results, you should refer to the battery discharge characteristics given by the battery manufacturer.
3. How to install UPS
For the installation of UPS, the general manufacturer will provide installation standards and connection diagrams.
Generally, the installation sequence of UPS is as follows:
1. Determine the installation location of UPS and battery cabinet when you go to the site.
2. Install the battery cable.
A. Determine the position of the battery switch, determine the direction of the positive and negative poles of the battery in the battery cabinet, and install the air switch and terminal on the battery cabinet.
B. Start the connection of the battery wire, connect the positive pole of the battery to the air switch.
C. The battery cord from the next layer to the previous layer should be wrapped with adhesive tape to prevent accidental short circuits and check the tightening of the bolts.
D. The positive and negative poles are clearly separated at the end to prevent wrong connection, the positive pole is connected to the connection terminal from the air switch, and the negative pole is directly connected to the terminal from the negative terminal post of the battery.
E. Check whether there are any irrelevant things in the battery cabinet.
F. Before connecting the battery cable to the host from the battery cabinet, measure the voltage of the battery with a multimeter, and check whether the positive and negative outlets are reversed.
3. Installation and wiring of the host
A. Correctly connect the input and output of the UPS and the battery connection between the battery cabinet and the host.
B. Use a multimeter to measure whether there is a short circuit in the connecting wire on the terminal block of the host.
C. Disconnect the mains input, output, and battery switches on the host, close the input switches of the distribution cabinet and the battery switches on the battery cabinet respectively, and measure whether the voltage is abnormal.
4. Boot up the host
After all the above steps are confirmed to be normal, turn on the machine according to the steps of the boot process, convert the mains power and battery, and measure whether the output voltage is abnormal
5. Access the load to see if the load is normal
The UPS and equipment are installed and powered on to start commissioning.
Fourth, UPS commonly used six major fault handling
1. When the mains power is available, the UPS will have a mains power outage alarm
Possible causes:
- The mains input is empty and trips;
- Poor contact of input AC line;
- The input voltage of the mains is too high, too low or the frequency is abnormal;
- The UPS input is empty or the switch is damaged or the fuse is blown out;
- The internal mains detection circuit of the UPS is faulty.
Solution:
- Check that the input is empty. Check the input line;
- If the mains power supply is abnormal, the generator can be not processed or started to supply power;
- Replace damaged air opens, switches, or fuses;
- Check the UPS mains detection loop.
2. When the mains power is normal, the UPS output is normal; When the mains power goes out, the load is also powered off
Possible causes
- Since the mains power is often under-voltage, the battery is in an under-voltage state;
- The UPS charger is damaged and the battery cannot be charged;
- Aging and damaged batteries;
- Load overload, UPS bypass output;
- The load is not connected to the UPS output;
- The battery pack of the long-delay model is not connected or has poor contact;
- The UPS inverter is not started (the UPS panel control switch is not opened), and the load is supplied by the mains bypass;
- The inverter is damaged, and the UPS bypasses the output.
Solution:
- Sufficient power to the battery when the mains voltage is normal; Start the generator to charge the battery; add a voltage regulator at the UPS input;
- Check the charger. replace the battery;
- Reduce load. Connect the load to the output of the UPS;
- Check whether the battery pack is connected correctly and well;
- Start the inverter to supply power to the load (turn on the panel control switch);
- Check the inverter.
3. UPS cannot be started
Possible causes
- The battery is not used for a long time, and the voltage is low;
- The input AC and DC power cables are not properly connected;
- The internal boot circuit of the UPS is faulty;
- The internal power supply circuit of the UPS is faulty or the power supply is short-circuited;
- The internal power device of the UPS is damaged.
Solution:
- Fully charge the battery;
- Check whether the input AC and DC lines are in good contact;
- Check the UPS boot circuit;
- Check the UPS power supply circuit;
- Check whether the components of the internal rectifier, boost, inverter and other parts of the UPS are damaged.
4. When the UPS is turned on, the input is empty and trips
Possible causes
- The input empty opening capacity is too small;
- UPS internal short circuit;
- The internal power device of the UPS is damaged;
- The user's mains air is open with leakage protection.
Solution:
- Replace the input empty on;
- Check whether the components of the internal rectifier, boost, inverter and other parts of the UPS are damaged;
- Check whether the components of the internal rectifier, boost, inverter and other parts of the UPS are damaged;
- Replace with an air opening without leakage protection.
5. When the UPS is in normal use, there is a sudden buzzer long beeping alarm
Possible causes
- The user has a large load or a large shock load to start;
- Sudden short circuit at the output;
- UPS internal inverter circuit failure;
- UPS protection and detection circuit malfunction.
Solution:
- When the load is put in, it is in the order of first large and then smaller; Increase the power capacity of the UPS;
- Check whether the output of the UPS is short-circuited;
- Check the UPS inverter. Check the internal control circuit of the UPS.
6. The UPS works normally but the load equipment is abnormal
Possible causes
- The UPS output zero ground voltage is too high;
- The UPS ground wire and the load equipment ground wire are not connected at the same point;
- The payload equipment is subject to abnormal interference.
Solution:
- Check the UPS grounding, if necessary, a 1-3KΩ resistor can be placed between the zero ground at the output end of the UPS;
- Connect the UPS ground to the same point as the load ground;
- Restart the load device.
UPS technical training program is attached