Trust UPS teardown

An uninterruptible power supply (UPS) is an electrical apparatus that provides emergency power to a load when the input power source or mains power fails. The on-battery runtime of most uninterruptible power sources is relatively short (only a few minutes) but sufficient to start a standby power source or properly shut down the protected equipment. A UPS is typically used to protect hardware such as computers, data centers, telecommunication equipment or other electrical equipment where an unexpected power disruption can cause serious problems.

In this tear-down I take a look at what is inside Trust Power Master PW-4095T – UPS – 950 VA UPS. First take a look at some basic information and the specifications on the device. This device is marketed as a reliable 950 VA UPS mains power protector for office and home usage. This device is designed to work with 230V AC voltage (can accept AC 170 – 280 V). It has Power Capacity of 950 VA. It uses line interactive UPS technology.

What is inside Trust Power Master PW-4095T – UPS – 950 VA UPS?

Here is view to the electronics.

There is main circuit board on the left. The heavy parts, battery and transformer, are on the right. The battery is clearly broken.

Here is a closer look at the main circuit board. It is interesting that the high current carrying wires going to transformer are bolted to the inverter switching transformer heatsinks. There are several relays on the circuit board, and I quess they are used to implement the input mains power transfer switch functionality and transformer tap switching for voltage regulation. The small circuit board sticking on the right is the telephone line surge protector. For mains power surge protection there seems to be a yellow VDR near mains power connector on the right.

A look at the specification of the broken battery. It looks like quite normal 12V sealed battery .The battery type is HR1234W from CSB battery. According to battery data sheet the battery has 34W @15min-rate to 1.67V per cell @25°C and maximum 130A discharge current.

Besides the battery, the transformer is also pretty big, because it needs to handle that 950 VA power.

This teardown ends here. Now some UPS theory related to this device:

According to APC white paper on different types of UPS systems Line Interactive is is the most common UPS design used for small business, Web, and departmental servers. In this design, the battery-to-AC power converter (inverter) is always connected to the output of the UPS. When the input AC power is normal, the inverter circuit works in “reverse mode” charging the batttery. When the input power fails, the transfer switch opens (disconnects the mains input connector from outputs) and the power flows from the battery to the UPS output (generates mains output waveform to output). You can find block diagrams of line ineractive UPS system from APC white paper  and pcguide.com.

The inverter/converter is also normally fitted with circuitry to filter out noise and spikes. Line Interactive design usually incorporates a tap-changing transformer to provide means of voltage regulation by adjusting transformer taps as the input voltage varies. This topology is inherently very efficient.  According to Line-interactive vs On-line Network UPS Systems and Which Should You Choose? article at the most basic level, line-interactive UPS systems are less expensive than on-line UPS systems (approximately 20 to 40% less, depending on the model and manufacturer), but they also provide less protection than on-line UPS systems.

 

20 Comments

  1. Tomi Engdahl says:

    Body diodes simplify UPS & energy recovery circuits
    http://www.edn.com/design/power-management/4443225/Body-diodes-simplify-UPS—energy-recovery-circuits?_mc=NL_EDN_EDT_EDN_designideas_20170103&cid=NL_EDN_EDT_EDN_designideas_20170103&elqTrackId=d049673c31354492ac64b93941f5299b&elq=7e3ada593c3f44e68d409ace630f6f29&elqaid=35378&elqat=1&elqCampaignId=30927

    This Design Idea illustrates a way to make use of MOSFETs’ parasitic body diodes in a power circuit that can be used in UPS and energy-recovery (e.g., regenerative braking) designs.

    Reply
  2. Tomi Engdahl says:

    Teardown of one UPS:

    EEVblog #1168 – Dumpster Diving UPS
    https://www.youtube.com/watch?v=qtDY6DEK-dE

    Dave scores a HP R1500 G3 rack mount Uninterruptible Power Supply (UPS) from the dumpster.
    Teardown time!

    Comments:

    While yes the batteries are hot swappable, it requires batteries to turn on. This is pretty much standard for APC units. It’s easy to get nice server sized APC units for free with dead batteries because they don’t turn on anymore, add a fresh set and they work perfectly. From what I can tell they by default disconnect the line input for safety, this means that the unit must be “on” to detect that line is available to switch to. So if the batteries are dead it won’t turn on. It’s a logical yet annoying standard, if something happens to the UPS to make it fail it results in complete isolation. Once the unit is on, as long as the line relay is held down it will power itself letting you swap batteries.

    Reply
  3. Tomi Engdahl says:

    How a UPS Works
    https://www.youtube.com/watch?v=E5RKBWhEUAU

    An explanation of how Uninterruptible Power supplies operate with animated block diagrams. Explains the differences between Transient Voltage and Surge Suppressors (TVSS), Automatic Voltage Regulators (AVR), Standby UPS’s, Line-interactive UPS’s and Online (Dual Conversion) UPS’s. This video also provides a summary of the features of the most common types.

    UPS topologies: standby, line interactive, online UPS systems
    https://www.youtube.com/watch?v=ijdB8szpmdA

    Explains the different types of UPS backup power systems, including line interactive, standby (offline) and online UPS topologies. Adjusts power voltage using a variac to demonstrate how a UPS supports a critical IT load. Live demonstration shows how on-line and line-interactive UPS technologies operate under varying power conditions.

    Reply
  4. Tomi Engdahl says:

    APC Smart-UPS 750 Teardown (Details on the Mains AC Side, All the Chips)
    https://www.youtube.com/watch?v=TT9je5yo7yM

    Teardown: Old APC Back-UPS units
    https://www.youtube.com/watch?v=srmpfMzEuPs

    A look at the output waveform, and how to change the charging voltage comes at the end of the video.

    Reply
  5. Tomi Engdahl says:

    EEVblog #504 – UPS Tutorial & Teardown
    https://www.youtube.com/watch?v=Fj7e3WGUKO8

    Dave explains the three main methods of Uninterruptible Power Supply design – Offline, Online, and Line Interactive. And then opens an APC 2200XL rack mount UPS to see how well it matches the classic block diagram theory. Will there be any surprises?

    Reply
  6. Tomi Engdahl says:

    Looking Inside a “Disposable” UPS
    https://www.youtube.com/watch?v=1zIuSiixyO8

    “That’s me, voiding warranties with glee since approximately 1983!”

    Today’s victim is a brand new APC Smart-UPS BN450M, purchased solely out of curiosity. I’ve been told by APC employees that the company felt there was a market for a UPS with a battery that can’t be serviced by the end user.

    I’d tell you I think that’s wasteful, but the truth of it is that very few owners of home/small business grade UPS products ever replace the batteries. They usually chuck the unit in the trash, donate it to a thrift store and buy a new unit when the old one fails a self test or (more commonly) fails to keep their equipment going when the power goes out.

    Reply
  7. Tomi Engdahl says:

    UPS SLA Batteries Teardown
    https://www.youtube.com/watch?v=QJb3ZWRRMlg

    Cheap chinese SLA Battery is a Rip off!

    Wow! I must say that Chinese battery is quite a rip-off. Never seen anything like it.

    Reply
  8. Tomi Engdahl says:

    Teardown and repair of APC-ES525 UPS
    https://www.youtube.com/watch?v=VZaja6vnEvs

    This low-cost UPS died on me after a few years of service so I decided to take it apart to see if it can be fixed.

    Reply
  9. Tomi Engdahl says:

    Teardown of a Eaton PowerWare 30kVA UPS for battery backup of servers
    https://www.youtube.com/watch?v=8efFFIwhKuA

    More pictures and descriptions
    http://kaizerpowerelectronics.dk/electronics/teardown-eaton-powerware-30-kva-ups/

    Reply
  10. Tomi Engdahl says:

    30 kVA UPS Teardown
    https://www.youtube.com/watch?v=FBjEee3nCZk

    Tearing down a 30 kVA UPS
    SUVTPM30KH APC UPS

    Fault found at the end of the video

    Reply
  11. Tomi Engdahl says:

    How To Repair a Computer UPS Cheap & Fast With Battery Replacement
    https://www.youtube.com/watch?v=7glF6Z7bfnw

    Today I woke up and my computer was off. After investigating I found out my UPS batteries were dead but I was able to replace them and I show you how in this video. Anyone of any skill level or technical knowledge can do this.

    Reply
  12. Tomi Engdahl says:

    Eaton 9395 Battery Ground Fault Test
    https://www.youtube.com/watch?v=hom2pG9ppvE

    Test video highlighting how the transformerless Eaton 9395 1100 kVA UPS handles a battery ground fault -

    https://www.eaton.com/us/en-us/catalog/backup-power-ups-surge-it-power-distribution/power-xpert-9395.html

    Reply
  13. Tomi Engdahl says:

    EEVblog #1168 – Dumpster Diving UPS
    https://www.youtube.com/watch?v=qtDY6DEK-dE

    Dave scores a HP R1500 G3 rack mount Uninterruptible Power Supply (UPS) from the dumpster.
    Teardown time!

    http://www.eevblog.com/forum/blog/eevblog-1168-dumpster-diving-ups/

    Reply
  14. Tomi Engdahl says:

    Dynamic Rotary UPS at Cisco’s Allen TX Data Center
    https://www.youtube.com/watch?v=xxcpBz_GMaU

    As part of providing production services documenting Cisco’s Allen Data Center, Cyclone produced this video that articulates the Dynamic Rotary UPS systems integrated into their newest Data Center in Texas.

    Hitec Power Protection – Diesel Rotary UPS Systems – corporate video
    https://www.youtube.com/watch?v=jZjgx4BADf8

    POWER TO RELY ON, PEOPLE TO RELY ON
    Hitec Power Protection develops, manufactures and delivers turnkey power solutions to ensure uninterruptible, continuous and conditioned power supply to mission critical processes. Core of the Hitec Power Protection solution are rotary UPS systems using flywheel energy storage. This is proven technology, based on more than 50 years of experience and supported by a global installed base of more than 1.500.000 kVA in high demanding industries.

    Reply
  15. Tomi Engdahl says:

    UPS topologies: standby, line interactive, online UPS systems
    https://www.youtube.com/watch?v=ijdB8szpmdA

    Explains the different types of UPS backup power systems, including line interactive, standby (offline) and online UPS topologies. Adjusts power voltage using a variac to demonstrate how a UPS supports a critical IT load. Live demonstration shows how on-line and line-interactive UPS technologies operate under varying power conditions. Check out how the line-interactive UPS technology will experience voltage drops, but the on-line double-conversion UPS technology can handle the same power variations without voltage drops.

    Reply
  16. Tomi Engdahl says:

    UPS Failure
    https://www.youtube.com/watch?v=Lhlhj-_7Rrc

    the failure in the UPS was a phase-to-phase short on the input 480 VAC circuit, apparently through the diodes or SCRs in the input AC side.

    Reply
  17. Tunnel Frog says:

    Great Content Exist Here.

    Reply
  18. Tomi Engdahl says:

    Make the Timely Move: Add a UPS to Your Battery/Cell Tester
    When the power goes out during battery and cell testing, data could easily get lost, leading to even more time spent for its recovery. Applying an uninterruptible power supply can avoid those headaches.
    https://www.electronicdesign.com/power-management/article/21135223/make-the-timely-move-add-a-ups-to-your-batterycell-tester?utm_source=EG+ED+Analog+%26+Power+Source&utm_medium=email&utm_campaign=CPS200625066&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R

    Reply

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