In the world of electric motors, the efficiency ladder keeps climbing. In a market that has just completed the move from IE2 to IE3 and on to IE4 Super Premium, eyes now turn to the next rung up: the IE5 Ultra Premium class. The best-known representative of IE5 is the synchronous reluctance motor (SynRM), which works differently from the familiar asynchronous design. So is IE5 truly the efficiency class of the future, or is it still too early for today's investment decision? In this article we examine IE5 and SynRM technology from the buyer's perspective, with realistic expectations.

For most businesses the right answer will not be a surprise: IE5 is a technology on the horizon, one to watch; but today, for a business running IE3 and wanting to move up a class, the most sensible, most accessible, and fastest-payback step is still IE4 Super Premium. Positioning IE5 as part of the medium-to-long-term plan sets both the right expectation and the right investment for today.

High-efficiency electric motor carrying the IE5 efficiency class label

Efficiency Classes: What Is the IE Ladder?

The efficiency of electric motors is defined by IE (International Efficiency) classes under the international IEC 60034-30 standard. These classes form a ladder showing how much of the energy drawn from the grid the motor converts into mechanical power:

  • IE1 – Standard Efficiency: An old class now banned from sale in most markets.
  • IE2 – High Efficiency: The transition-era class; today insufficient on its own.
  • IE3 – Premium Efficiency: Today's mandatory baseline class; the backbone of the market.
  • IE4 – Super Premium Efficiency: The highest practical class accessible today; the target of efficiency-focused investment.
  • IE5 – Ultra Premium Efficiency: The next rung up; not yet widespread, a class on the horizon.

Each rung aims to reduce losses by a certain proportion compared with the previous one. IE5 promises to lower losses even further than IE4; but achieving this gain with a standard asynchronous design becomes increasingly difficult. This is exactly where synchronous reluctance (SynRM) technology comes in.

What Is a Synchronous Reluctance (SynRM) Motor?

In a classic asynchronous motor the rotor "chases" the rotating magnetic field, and losses arise in the rotor because of the slip between them. A synchronous reluctance motor, on the other hand, works on a different principle: it uses a specially shaped rotor that guides the magnetic flux and carries no windings or magnets. The rotor turns with torque created by the difference in reluctance (magnetic resistance) and runs at synchronous speed with the rotating field.

This structure has two major advantages:

  • Rotor losses almost disappear: Because there is no current-carrying conductor in the rotor, copper loss and slip loss are largely eliminated.
  • Low rotor temperature: Fewer losses mean less heating, and longer bearing and insulation life.

SynRM motors usually contain no rare-earth magnets; this is an advantage in terms of supply. But they have an important condition: most do not run direct-on-line and must be commissioned together with a variable frequency drive (VFD). This means the purchase decision covers not only the motor but also drive and installation compatibility.

Cross-section of a synchronous reluctance motor rotor with magnetic flux barriers

Why Is IE5 Still a Class "On the Horizon"?

Although IE5 is technically available, several conditions must mature before it spreads across the market:

  • Mandatory drive dependence: Because SynRM motors do not run without a VFD, every IE5 investment is in fact a motor + drive + parameterization package. This increases the initial investment and the complexity of commissioning.
  • Limited stock and product breadth: Against the wide stock variety of IE3 and IE4 motors, the IE5 product range is still narrow and often requires project-based supply.
  • Payback period: The extra efficiency gain from IE4 to IE5 is smaller than from IE3 to IE4. Therefore the extra investment requires more running hours to pay for itself.
  • Regulatory maturity: There is not yet widespread regulation making IE5 mandatory; this is a factor slowing its spread.

None of this means IE5 is a bad technology; on the contrary, in the right application it is very valuable. It is only that the "let's make every motor IE5 right away" approach is not economically realistic today.

Today's Right Step: IE4 Super Premium

For a business running IE3 and wanting to move up a class, today's most sensible choice is clear: IE4 Super Premium. The reasons can be listed as follows:

  • Wide stock and fast supply: IE4 motors are now stocked in wide variety across standard kW, speed, and mounting types; this means short lead time.
  • Direct-on-line capability: Most IE4 asynchronous motors fit existing installations without a drive requirement, simplifying commissioning.
  • Faster payback: The efficiency gain achieved in the move from IE3 to IE4 repays the extra investment within a reasonable time in most running profiles.
  • Compatibility with existing infrastructure: Thanks to the same IEC frame and mounting dimensions, IE4 fits in place of IE3 exactly.

So if you are going to make an efficiency-focused investment today, placing your target realistically at IE4 is the soundest strategy. Comparing IE3 and IE4 options with current electric motor prices lays the foundation of the right investment. Reviewing the payback comparison between IE4 and IE5 also clarifies your decision.

How Should IE5 Be Positioned in the Plan?

Not buying IE5 today does not mean ignoring it. The right approach is to position IE5 in the medium-to-long-term investment plan as a "technology to watch." Especially in the following situations, IE5/SynRM can make sense even today:

  • Very high running hours: In applications running thousands of hours a year, almost without interruption, the extra efficiency gain repays faster.
  • Lines already using a VFD: In applications already using a drive for speed control, SynRM's drive requirement creates no extra cost.
  • Plants where energy cost is critical: In businesses where the energy bill is a large share of total cost, every efficiency rung gains importance.

It is wise to carry out a supply and suitability assessment for projects of this nature. Through a technical supply discussion it is possible to evaluate together whether it is right for your current line to move to IE5 today or later. Planning done with manufacturer assurance links both today's IE4 investment and the future IE5 transition.

Frequently Asked Questions

Does an IE5 motor run direct-on-line?

Usually no. Synchronous reluctance (SynRM) motors, the best-known technology of the IE5 class, mostly do not run direct-on-line and must be commissioned with a variable frequency drive (VFD). Therefore an IE5 investment should be evaluated as a motor + drive + parameterization package.

Should I move from IE3 straight to IE5 today?

For most businesses the most sensible and accessible step is IE4 Super Premium. IE4 offers wide stock variety, fast supply, and a shorter payback period. IE5 is better evaluated for special applications with very high running hours that already use a VFD.

Do SynRM motors contain rare-earth magnets?

Generally no. In synchronous reluctance motors there are no windings or magnets in the rotor; torque is produced by the reluctance difference arising from the rotor's shaped magnetic structure. This is an advantage in supply and cost; however, the motor's requirement to run with a VFD does not change.