Can introduce UPS so comprehensively, it is not shei!

UPS type, function, principle

What is UPS

UPS-Uninterrupted Power System; an energy conversion device that uses battery chemistry as backup energy to continuously provide (AC) power to user equipment in the event of a grid failure such as a mains failure.

Why use UPS

UPS's four functions

1. No power failure function to solve power grid blackout problems;

2. AC voltage regulation function to solve the problem of severe fluctuation of network voltage;

3. Purification function to solve the problem of power grid and power pollution;

4. Management functions to solve the problem of AC power maintenance;

The main functions of UPS:

Achieve isolation between the grid and the appliance;

Realize the uninterrupted switching of two power sources;

Provide high quality power;

Voltage conversion and frequency conversion functions;

Provide backup time after power failure.

UPS type

According to different working principles, UPS is divided into:

Offline (backup UPS, interactive UPS)

Online UPS

According to different power supply systems, UPS is divided into: single-input single-out UPS, three-input single-out UPS, three-in and three-out UPS.

According to different output power, UPS is divided into:

Micro < 6kVA

Small 6-20kVA

Medium 20-100KVA

Large >100kVA

According to the battery position, UPS is divided into:

Battery built-in UPS (standard model)

Battery external UPS (long delay model)

According to different multi-machine operation modes, UPS is divided into:

Series hot backup UPS (for medium and small power machines)

Alternate series hot backup UPS (small and medium UPS)

Direct parallel UPS (for medium to high power)

According to the characteristics of the transformer, the UPS is divided into: high frequency UPS (high frequency machine), power frequency UPS (power frequency machine)

According to the output waveform, the UPS is divided into: square wave output UPS, step wave (quasi-sine wave) UPS, sine wave output UPS.

UPS system structure and principle

The monitoring platform is also one of the most important components of UPS.

The basic principle of UPS

Backup UPS operating principle

When there is mains supply, the mains supply is directly supplied to the load through the switch, and the inverter does not work. In addition, the mains charges the battery through the charger.

After the power failure, the inverter is started, and the energy stored in the battery is supplied to the load through the inverter and the switch.

Power level 0.25-2KVA

Interactive UPS operating principle

The main difference between the online interactive UPS and the backup type is that the inverter and the charger are combined into one; the output is tapped by the tap of the transformer to realize the sectional voltage regulation.

Power level around 0.7-20KVA

Online UPS operating principle

Regardless of whether the grid voltage is normal or not, the AC voltage used by the load must pass through the inverter circuit, that is, the inverter circuit is always in operation.

Power level 0.7-1500KVA or so

Delta conversion UPS operating principle

The delta converter and the compensation transformer implement a voltage stabilizing function, and the main converter is a bidirectional converter. The frequency cannot be stabilized.

Power level 10-480KVA or so

Comparison of four UPS

UPS power supply system

A complete UPS power supply system consists of front-end power distribution (mains, generators, power distribution cabinets), UPS host, battery, back-end power distribution, additional background monitoring or network monitoring software/hardware.

UPS monitoring system

UPS network monitoring system = intelligent UPS + network + monitoring software

The network monitoring software consists of the following three parts:

SNMP card

Monitoring station software

Safe shutdown procedure

UPS monitoring network

UPS quality selection and configuration options

UPS quality selection

UPS-load: output / machine indicators

Output voltage standard and accuracy (220/380VAC ± 1%)

Output frequency standard and accuracy (50HZ ± 0.01%)

Output power factor (0.7-1)

Output overload / short circuit resistance (125% rated current, 10min 150% rated current, 60s)

Three-phase unbalanced capacity (100% unbalanced load, voltage imbalance <±5%)

Dynamic response (100% load, transient voltage fluctuation <5%, recovery time: ≤20ms)

Efficiency (90-94%)

Noise (50-75db)

Environmental indicators (temperature 0 ~ 40 ° C), humidity, altitude <1000 meters).

UPS machine index - efficiency calculation

UPS parts efficiency:

SCR rectifier 99%; IGBT rectifier 98%, IGBT inverter efficiency 96%, transformer efficiency 98%, filter 99%

The efficiency of traditional UPS:

SCR rectification (99%) × IGBT inverter (96%) × output TX (98%) = 93%

12-pulse traditional UPS efficiency:

Input phase shift TX (98%) × double SCR rectification (98%) × IGBT inverter (96%) × output TX (98%) = 90%

New UPS efficiency calculation:

IGBT rectification (98%) × IGBT inverter (96%) = 94%

UPS - Battery: Battery Management

Charging protection (overvoltage and overcurrent charging protection, temperature compensation)

Discharge protection (shutdown voltage setting and adjustment, automatic tripping)

Intelligent battery management (detection and alarm)

Backup time calculation and display: rated load backup time T

75% rated load 1.6T; 50% rated load 2.5T; 33% rated load 4T

Charging capacity and charging time: 10% to 25% of the capacity to charge capacity

Charging time calculation: T = AH / I charging × (charging efficiency 80%)

UPS configuration and selection

UPS classification and selection

Working methods: backup, interactive, online;

Capacity: low power (1 ~ 10KVA); medium power (20 ~ 60K); high power (80 ~ 1000KVA)

Applicable environment: commercial grade, industrial grade, power plant dedicated, onboard or marine

Output transformer: high frequency machine, power frequency machine. Low power: APC, Santak, Kestar, PCM

Medium power: Powerware, MGE, Emerson-Liebert, Delta, Santak

High-power Emerson-Liebert, MGE, Powerware, Chloride-Siemens, Socomec-Sicon, GE-Imv, Best-Borri

Other common brands: Kelong, Champion, East, Xerox, Fuhua, Youma, Baohe, Stone, Best, Gamma, Relex, Powerland ), Sendon, Deltec, Toshiba, APC-Gutor, AEG (German General Electric), Protect (Protec).

Capacity and model selection

Battery calculation and configuration

Power distribution part: cables and switches

Capacity and model selection

User load, redundancy

Load properties: IT, inductive load, use environment - harmonics, transformer

Computer room power distribution design: incoming line

Model cost and competitive advantage.

User load; UPS output redundancy (70 to 80%)

The load peak factor (3:1) cannot exceed the inverter overload capability

Load apparent power (KVA) cannot exceed UPS rated power * Power factor conversion factor

Three-phase load imbalance <30%.

Industrial grade UPS

Harsh electrical and physical environment: power line voltage / frequency fluctuations, surge impact, peak sag, high frequency interference, environmental temperature and humidity instability, dust, corrosion, etc.

Structure: input and output double isolation, steel plate chassis, high IP protection level.

Application areas: steel, chemical, electric power, automotive, paper, coal, oil, tunnel

Load type: heavy-duty machinery, production line equipment, DCS system, etc.

UPS working loss, ventilation, air conditioning configuration

Full load loss (KW) = kVA Cos × (6 ~ 7.5%) air conditioning capacity

UPS capacity	40KVA	80KVA	100KVA	160KVA	200KVA	300KVA	400KVA	600KVA	800KVA
Ventilation volume cubic meter / h	2200	2400	2590	3500	3700	3900	4400	7500	9300

Output power conversion - altitude, 1% derating per 100 meters above sea level (typical UPS working altitude: 1000 meters)

Altitude	1000 meters	1500 meters	2000 meters	2300 meters	3000 meters
UPS output power conversion	100%	85%	79%	75%	69%

Battery calculation and configuration

Accurate calculation: constant power calculation

1. The cutoff voltage is determined:

1.67V/cell<discharge for 30 minutes; 1.75V/cell discharge for 30~60 minutes;

1.83V/cell>discharge for 60 minutes

2. Calculate constant power data for each Cell battery:

3. Select the battery specification that meets the calculation result according to the manufacturer's constant power discharge data table.

Power distribution part: cables and switches

Input switch capacity and cable specifications:

Three-phase electrician speed algorithm: input current (A) = 1.8XKVA, switching factor X1.2

Single-phase electric speed algorithm: input current (A) = 5XKVA, switching factor X1.2

Output switch capacity and cable specifications:

Three-phase electrician speed algorithm: output current (A) = 1.5XKVA, switching factor X1.2

Single-phase electric speed algorithm: output current (A) = 4XKVA, switching factor X1.2

Battery switch capacity and cable specifications: Discharge current (A) = kVA ï‚´ Cos / U battery voltage switching factor (X1.2)

Cable length and pressure drop: such as 70mm line resistance 0.26Ώ/km

Zero line and ground line specifications: zero line = 1 to 1.5 times phase line, ground line = phase line

Power distribution part: cable and switch specifications

Cable rated current simple algorithm

Cable specification	1/1.5/2.5	4/6	10/16	25/35/50	70/95/120	150/185	240	300
Rated current	X8A	X6A	X4A	X3A	X2.5A	X2A	X1.5A	X1.2A

Open specifications: R10, R16, R20, R25, R32, R40, R50, R63, R80, R100, R125, R160, R200, R250, R320, R400, R630, R800, R1250.

Isolation transformer

380V/380V output isolation transformer for high frequency machine: capacity KVA=UPS KVA

The â–³/Y0 type isolation transformer is selected, the output neutral point is grounded, and the Y/Y type transformer bypass backflow will cause the DC voltage to be too high.

UPS installed 380V/220V output isolation transformer: output capacity loss 20~30% has interference feedback to the inverter, high efficiency selection, interference small transformer.

Bypass isolation transformer: achieves zero-line electrical isolation.

UPS basic maintenance

General requirements for UPS maintenance

1. The UPS mainframe should be placed on the site to guide the operation.

2. The setting information of UPS parameters should be fully recorded, properly archived and kept updated.

3. Check if various automatic, alarm and protection functions are normal.

4. Regularly perform various functional tests of UPS.

5. Regularly check the contact status of the lead wires and terminals of the main unit, battery and power distribution parts, check whether the connection of the feeder bus, cable and soft connector is reliable, and measure the voltage drop and temperature rise.

6. Always check the operation of the equipment and the fault indication is normal.

7. Regularly check the appearance of the components inside the UPS and find that the abnormalities are handled in time.

8. Regularly check whether the operating temperatures of the main modules and fan motors of the UPS are abnormal.

9. Keep the machine clean and regularly clean the air vents, fans and filters.

10. Regularly carry out UPS battery pack loading test.

11. All localities should select the appropriate tracking rate according to the changes in the local mains frequency. When the input frequency fluctuates frequently and the rate is high, it is prohibited to perform the inverter/bypass switching operation when the UPS tracking range is exceeded. In the case of oil supply, special care should be taken to avoid this.

12. The UPS should use an open battery rack to facilitate the operation and maintenance of the battery.

UPS maintenance project and periodic table

1 UPS daily inspection project:

The main contents are: check the control panel, confirm that all indications are normal, all indication parameters are normal, there is no alarm on the panel; check for obvious high temperature, no abnormal noise; make sure that the ventilation grid is not blocked; call out the measured parameters to see if there is any Does not match the normal value.

2 UPS weekly inspection project:

The main contents of the weekly inspection are: measuring and recording the battery charging voltage, battery charging current, UPS three-phase output voltage, UPS output line current. If the measured value is significantly different from the previous one, record the size, type and location of the new load.

UPS monthly, quarterly, and annual maintenance projects:

Battery management for UPS power supplies

The battery is an important part of the UPS. A large proportion of the UPS's faults are caused by battery problems. The performance of the battery directly affects the reliability of the system. In order to guarantee the service life of the battery, in addition to maintaining normal temperature and daily maintenance, automatic management of the battery is a crucial factor.

The UPS power supply automatically manages the battery including automatic floating charge switching control, battery pre-alarm shutdown, periodic automatic maintenance, manual battery self-test and many other advanced functions that can improve battery life. It also has battery fault detection and battery discharge backup time. Forecasting and battery characteristic curve management.

Automatic, floating charge conversion

The battery charging process can automatically realize equalization and floating charge automatic conversion according to the battery current. The set charge and float charge criterion is: I≤0.01C.

2 Battery float voltage compensation: (take 2V battery as an example)

When the battery is in the floating state, the float voltage can be compensated according to the temperature. The temperature compensation is centered at 20 °C, and the compensation is fully compensated in the range of 10 °C - 40 °C.

Temperature T>40, T=40; if T<10, T=10

The average cell voltage of the battery should be adjusted to: V=V0+(20-T)×0.003

Among them, V0 is the battery float voltage given by the battery manufacturer at 20 °C, which can be set according to different batteries at the initial power-on. The default is 2.23V. The average charging voltage is not compensated, and the default single cell charging voltage is 2.35V.

3 When the charge is limited:

If the battery is in the equalizing state for 12 hours, the control system will force the floating state. The setting condition is that when the equalizing time reaches the set value, it will automatically switch to the floating state.

4 Discharge management:

Set the cutoff voltage of the battery discharge to 1.8V per cell. The actual cutoff voltage will fluctuate around this value as the battery ages. The cutoff voltage is 1.8V per cell, and high power discharge has been considered. The battery capacity is attenuated in the case.

UPS battery automatic test

The capacity test of the UPS battery can be manually tested or realized by the UPS battery automatic test function. The manual test method can be referred to the battery capacity test method in the DC power supply system. The following describes the automatic test function of the UPS.

This test can only be performed under the following conditions:

The inverter is running;

The inverter is not overloaded;

The backup power supply (bypass power supply) is present and meets the requirements;

The inverter is synchronized with the bypass power source;

The battery must be fully charged.

The UPS battery auto test function is set according to the following three points:

Time interval (test period can be set to 10 days - 150 days)

Date and time of automatic battery test

The default alarm mode when there is a problem with the battery

When the battery test is started, the rectifier voltage will drop below the rated voltage of the battery pack, and above the shutdown voltage of the inverter, if the battery can discharge as required within the specified load and the specified time, the UPS gives a positive signal indicating that the battery It is good; if the battery fails to discharge as required within the specified load and within the specified time, the UPS gives a negative signal indicating that the battery needs to be replaced. However, since the rectification/charger voltage is greater than the inverter shutdown voltage value, the rectification/charger voltage is still supplied to the inverter, so that the output voltage is not interrupted.

UPS common troubleshooting

1 When the mains is powered, the UPS has a mains power failure alarm.

Possible Causes

1) The mains input is open and tripped.

2) The input AC line is not in good contact.

3) The mains input voltage is too high, too low or the frequency is abnormal.

4) The UPS input is open or the switch is damaged or the fuse is blown.

5) The UPS internal mains detection circuit is faulty.

Approach

1) Check that the input is open.

2) Check the input line.

3) If the mains abnormality can not be processed or start the generator power supply.

4) Replace the damaged air switch, switch or fuse.

5) Check the UPS mains detection circuit.

2 When the mains is normal, the UPS output is normal; after the mains is cut off, the load is also powered off.

Possible Causes

1) Since the mains is often low voltage, the battery is under voltage.

2) The UPS charger is damaged and the battery cannot be charged.

3) The battery is aging and damaged.

4) Load overload, UPS bypass output.

5) The load is not connected to the UPS output.

6) The battery pack of the long delay model is not connected or has poor contact.

7) The UPS inverter is not started (the UPS panel control switch is not turned on), and the load is supplied by the mains bypass.

8) Inverter damage, UPS bypass output.

Approach

1) A. Fully charge the battery when the mains voltage is normal.

B. Start the generator to charge the battery.

C. Add a voltage regulator to the UPS input.

2) Check the charger.

3) Replace the battery.

4) Reduce the load.

5) Connect the load to the output of the UPS.

6) Check if the battery pack is connected and connected.

7) Start the inverter to supply power to the load (open the panel control switch).

8) Check the inverter.

3 The UPS cannot be started.

Possible Causes

1) The battery is not used for a long time, and the voltage is low.

2) The input AC and DC power cables are not connected.

3) The internal startup circuit of the UPS is faulty.

4) The UPS internal power supply circuit is faulty or the power supply is shorted.

5) The internal power device of the UPS is damaged.

Approach

1) Fully charge the battery.

2) Check if the input AC and DC lines are in good contact.

3) Check the UPS boot circuit.

4) Check the UPS power circuit.

5) Check if the components inside the UPS internal rectification, boost, inverter, etc. are damaged.

The buzzer sounds suddenly when the UPS is in normal use.

Possible Causes

1) The user has a large load or a large shock load to start.

2) The output is suddenly shorted.

3) The internal inverter circuit of the UPS is faulty.

4) UPS protection and detection circuit malfunction.

Approach

1) A. When the load is input, it should be in the order of first big and then small.

B. Increase the power capacity of the UPS.

2) Check if the output of the UPS is short-circuited.

3) Check the UPS inverter.

4) Check the UPS internal control circuit.

6 The UPS is working properly but the load device is abnormal.

Possible Causes

1) The UPS output zero ground voltage is too high.

2) The UPS ground wire and the load equipment ground wire are not connected at the same point.

3) The load device is subject to abnormal interference.

Approach

1) Check the UPS grounding, if necessary, between the zero ground of the UPS output and a 1-3KΩ resistor.

2) Connect the UPS ground to the load ground to the same point.

3) Restart the load device.