PECO and Conventional Passive Systems
What is the same, what is different, and what is worth asking any supplier in this category.
Start with What Is Not Different
PECO Powersaver uses a zig-zag autotransformer and a fixed voltage step-down. So do conventional passive energy-saving systems. We do not claim a different physical principle, and any supplier claiming one in this category should be asked to explain it.
Passive equipment of this type has been installed in commercial and industrial buildings for decades. It is established technology, not a novelty. The behaviours that follow from a zig-zag winding — phase coupling, and a degree of reduction in fifth- and seventh-order harmonic current — are characteristic of the type, not of any one product.
PECO differs in degree rather than in kind. What follows is where, and why.
Four Design Decisions
The differences are in engineering choices, not in physics.
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01
The winding
The conventional arrangement in this category winds 96 turns and adds four to reach 100 — one continuous winding, with the 4 % step-down taken from a tap along it. The whole winding carries load current, and its resistance determines how much heat the device produces.
PECO winds a full 100, then adds four more in reverse as a separate winding, tied to the main winding at both ends. Because of that bond, the auxiliary path carries more current at lower resistance than its own conductor would allow on its own. The arrangement is protected by Korean Patent No. 10-2546570.
The measurable consequence is efficiency: typically 99.8 % or higher, measured at 99.7 % to 99.83 % across models, taken from the product manuals supplied with individual units.
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02
The interconnection
A zig-zag winding carries each phase’s output through sections sitting on different core limbs. Each crossing is a transition point.
The PECO main winding zig-zags across three phases and the auxiliary winding across two, giving six — as in a conventional arrangement. Tying the two windings at both ends adds three more. Nine in total, where a conventional arrangement has six.
This is a structural difference, countable from the winding diagram.
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03
The by-pass
PECO ships as a complete assembly with an integrated automatic transfer switch. The transformer can be taken out of circuit while the facility continues to be supplied.
This matters twice over. It is a protective function under overload — and it is what makes direct measurement possible, because the facility can be operated on both paths and compared on the same meter. Equipment without an integrated by-pass cannot be evaluated this way.
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04
The scope of assessment
Under the Low Voltage Directive a manufacturer may self-declare conformity. ATECELECTRIC obtained third-party attestation from TÜV SÜD Product Service GmbH voluntarily, covering the complete standard range of 39 models from 100 to 3,000 kVA and rated input voltages from 380 to 480 VAC.
At a Glance
| Design decision | Typical of this equipment category | PECO Powersaver |
|---|---|---|
| Primary design objective | Voltage step-down | Minimising the loss and heat the device itself adds |
| Winding arrangement | Continuous tapped common winding, 96 + 4 turns | Full zig-zag main winding + separate reverse auxiliary winding, 100 + 4 turns, tied at both ends |
| Zig-zag transition points | Six | Nine |
| Conductor used for the same rating | — | More · heavier assembly |
| Voltage ratio | Tapped, sometimes field-adjustable | Fixed 4 %, no tap changer |
| Scope of supply | Transformer, or transformer in an enclosure | Complete assembly with protection, transfer and indication |
| Taking the unit out of circuit | Requires disconnecting the supply unless a by-pass is provided separately | Integrated Saving / By-pass path |
| Establishing the result | Depends on the supplier | Direct comparison at the same meter, under a published protocol |
“Typical of this equipment category” describes the conventional configuration of passive zig-zag energy-saving equipment. It is not a statement about any particular manufacturer’s product, and individual products vary.
Six Questions Worth Asking Any Supplier
Including us. If a supplier cannot answer these clearly, that is information in itself.
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01
What is the efficiency of the device itself, and where does that figure come from?
A device installed in series consumes something. Ask for a number, and ask whether it comes from a test report or from marketing literature.
PECO Typically 99.8 % or higher — 99.7 % to 99.83 % across measured models, stated in the product manual delivered with each unit.
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02
Which directive does the CE marking cover, and who assessed it?
CE marking is not a single certificate. It is declared per directive, and under some directives the manufacturer may self-declare. Ask which body assessed the product, and which models the assessment covers.
PECO TÜV SÜD Product Service GmbH, Attestation No. N8A 103329 0002, Low Voltage Directive 2014/35/EU, covering all 39 models from 100 to 3,000 kVA.
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03
Can the device be taken out of circuit without disconnecting the facility?
This determines whether the effect can ever be measured directly, and whether the installation can be reverted if it does not suit the site.
PECO Yes, through the integrated By-pass path.
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04
How will the saving be measured, and in what unit?
Accumulated kWh at the billing meter is what appears on the invoice. Average kW over selected periods is not the same thing. Ask which will be used, and how comparison periods will be matched.
PECO Accumulated kWh, under a published protocol.
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05
What happens to data that is excluded from the comparison?
Every measurement on a working facility contains anomalies. Ask when the exclusion rule is defined — before or after the results are seen — and whether the unfiltered data will also be reported.
PECO Exclusion criteria are agreed before measurement; both the complete and filtered data sets are reported.
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06
Under what conditions is the equipment not suitable?
A supplier who says their equipment suits every installation has not assessed yours.
PECO Conditions under which we do not recommend the system are published.
What We Do Not Claim
- We do not claim that PECO uses a different physical principle. It does not.
- We do not claim that conventional passive systems do not work. Many do.
- We do not claim a higher saving percentage than any other supplier, because we do not publish one at all.
- We do not claim that reduction of fifth- and seventh-order harmonic current is unique to PECO. It is characteristic of zig-zag equipment generally, and we are not offering a harmonic filter.
What we claim is narrower and checkable: a winding architecture protected by patent; nine zig-zag transition points where a conventional arrangement has six; efficiency figures taken from product manuals rather than brochures; third-party attestation covering the complete standard range; and a system that can be switched out of circuit, so that its effect is measured rather than asserted.
The Review Comes First
Before any proposal, we review the single-line diagram, transformer rating, voltage range and load composition. If PECO is not suitable for the installation, that is what we will say.