A UPS appears to be a single, single unit from the outside, but inside it contains many interconnected, critical spare parts . A problem in any one of these parts can disable the entire system.
This article clearly explains which parts are found inside a UPS, what they do, and which ones are more prone to failure 👇
1️⃣ Batteries
It is the most frequently modified part of a UPS.
What is it used for?
It powers the load (camera, server, NVR, POS, etc.) when the power goes out.
Things You Need to Know
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VRLA (dry type) batteries are generally used.
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2–4–6–8 units can be connected in series.
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Average lifespan: 2–4 years
⚠️ When the battery is faulty, the UPS may appear to be working, but it will shut down instantly when the power goes out .
2️⃣ Inverter Card
We could call it the heart of UPS.
His/Her job
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DC electricity from the battery
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It converts the electricity to AC electricity that the devices will use.
Malfunction Symptoms
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The UPS never turns on.
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The fuse keeps blowing.
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Smell of burning / soot
👉 Inverter failures are generally very costly to repair .
3️⃣ Control Board (Main Board)
The brains of UPS.
What does it do?
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It monitors voltage, current, and load.
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Manages alarm and screen information.
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It runs protection scenarios.
If this card fails, the UPS will:
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It gives a false alarm.
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It misreads the load.
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It closes randomly.
4️⃣ Fans (Cooling System)
One of the most neglected but also one of the most critical components.
Why is it important?
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A UPS is a continuously operating device.
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If it can't dissipate heat, the cards will burn out.
What does a fan malfunction do?
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Overheating
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Automatic shutdown
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Card damage in the long term.
🛑 If the fan is not working, the UPS should never be used for an extended period .
5️⃣ Relays
It controls the flow of electricity.
Tasks
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Mains ↔ battery switching
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Bypass line management
In case of relay failure:
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Clicking sounds
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Late reaction
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Sudden interruptions occur.
6️⃣ Insurances
This is the UPS's self-protection mechanism .
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It shuts down the system in case of overcurrent.
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It prevents the cards from burning.
If the fuse blows:
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Not "The problem is solved"
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That means there's a bigger problem .
7️⃣ LCD / LED Display Panel
The point of contact between the user and the UPS.
It shows:
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Load percentage
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Battery status
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Error codes
If the control panel isn't working, the user is left stranded even if the UPS is functioning properly.
8️⃣ Bypass Card / Static Bypass
It is especially found in online UPS systems .
What is it used for?
Even if the UPS malfunctions:
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It supplies electricity directly to the load.
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It prevents the system from shutting down completely.
It is vital in server and CCTV infrastructures.
| Piece | Frequency of Change |
|---|---|
| Battery | ⭐⭐⭐⭐⭐ |
| Fan | ⭐⭐⭐⭐ |
| Relay | ⭐⭐⭐ |
| Insurance | ⭐⭐ |
| Cards | ⭐ |
