What is BK 220V SinglePhase Control Transformer？

Need a clean, stable power supply for your control circuits? BK has you covered.

In factories, workshops, and automation systems, there's a small device that rarely gets noticed — until it stops working. When a CNC machine's PLC loses power, the contactors chatter, or the indicator lights go dim, production stops. And more often than not, the culprit is a control transformer that wasn't up to the job.

The BK series singlephase control transformer is built to keep control circuits running — reliably, continuously, and safely.

What Is a BK 220V SinglePhase Control Transformer?

A BK series control transformer is a singlephase drytype stepdown transformer designed specifically for control circuits, local lighting, and indicator systems in industrial and commercial applications. It takes the main supply voltage — typically 220V or 380V — and steps it down to the lower voltages that PLCs, relays, contactors, solenoids, and indicator lights actually need.

Unlike power transformers that feed heavy motors and heating elements, the BK transformer is purposebuilt for the "brain" side of the equipment. It provides a dedicated, clean, isolated power supply for control systems — keeping them stable even when the main power bus fluctuates.

Available capacities range from 25VA up to 100kVA, with input voltages from 220V to 500V and output voltages customizable from 6V to 220V. That means whether you're powering a single indicator light or a complex PLC system, there's a BK transformer that fits.

How BK 220V SinglePhase Control Transformer Works？

The principle is straightforward: electromagnetic induction.

The transformer has two separate windings — primary (input) and secondary (output) — wrapped around a laminated silicon steel core. When AC voltage is applied to the primary winding, it creates a magnetic field in the core. That field induces a voltage in the secondary winding.

The voltage ratio is determined by the turns ratio. Put simply: more turns on the secondary = higher output voltage; fewer turns = lower output voltage.

This isn't an autotransformer. The primary and secondary windings are electrically isolated from each other — which means surges, noise, and ground faults on the main supply don't pass through to the control circuit.

Key Features

1. Clean, stable power for control circuits

The BK transformer isolates sensitive control electronics from the dirty power on the main bus. PLCs don't glitch. Contactors don't chatter. Sensors don't drift.

2. Wide voltage range

Input voltages from 220V to 500V at 5060Hz — compatible with almost any industrial supply. Outputs can be customised to 6V, 12V, 24V, 36V, 48V, 110V, 127V, 220V, or any voltage in between.

3. Compact, panelfriendly design

The BK transformer is a shelltype, verticalmounting unit. It takes up minimal space in a control cabinet and is easy to install.

4. Pure copper windings (optional aluminium)

Copper windings mean lower resistance, less heat, and longer life. Some models use aluminium for costsensitive applications.

5. High efficiency

Efficiency ratings can reach 98% , meaning very little energy is wasted as heat.

6. Builtin terminal cover

The topmounted terminal cover protects connections from accidental contact and dust — and it's removable for easy wiring.

7. Customisable

Input voltage, output voltage, capacity, connection type — all can be tailored to your specific requirements.

Where You'll Find BK Transformers？

The BK series is widely used wherever control circuits need reliable power:

In short: anywhere that needs a reliable, isolated power supply for control circuits.

How to Choose the Right BK 220V SinglePhase Control Transformer？

Picking the right size is straightforward, but a few mistakes can cause trouble.

Step 1 — Add up your loads

List every device the transformer will power: PLCs, relays, contactors, solenoids, indicator lights, sensors. Add their VA ratings — not just watts. Contactors and relays draw reactive power, so use VA if possible.

Step 2 — Apply a safety margin

What Makes a Good BK 220V SinglePhase Control Transformer?

Not all control transformers are built the same. A good BK transformer should have:

Pure copper windings — better conductivity, less heat, longer life

Highquality silicon steel core — low losses, low noise, high efficiency

Class F or H insulation — rated for 155°C or 180°C continuous operation

Vacuum impregnation — seals the windings against moisture, dust, and vibration

Rigorous factory testing — insulation resistance, dielectric withstand, and performance verification

Final Thoughts

The BK 220V singlephase control transformer isn't the most glamorous component in a control panel. It doesn't have a touchscreen or a software update.

But it does one thing very well: it keeps control circuits running — cleanly, reliably, and continuously.

For machine tools, automation systems, and industrial facilities that can't afford voltagerelated downtime, the BK transformer isn't optional. It's infrastructure. It sits in the corner of the control panel, quietly doing its job, year after year — until you forget it's even there.

And that's exactly how it should be.

A good control transformer isn't expensive. A bad one is.