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When buying an IE3 electric motor or replacing an existing motor, the most reliable way to choose the right product is to read the motor's nameplate (rating plate) correctly. The nameplate is the motor's identity: it carries all the information that defines the order, from its power and speed to its voltage and efficiency class. A misread nameplate leads to the wrong motor arriving and to field incompatibility. As HEM Motor, a manufacturer and supplier, in this article we explain every value on an IE3 motor nameplate from a buyer's perspective, together with what it means for purchasing.
The explanations below are a practical reading guide both for purchasers selecting a new motor and for businesses wanting to replace their existing motor one-to-one. Under each heading, you will find where on the nameplate to see the relevant value and why it matters for the order.
Where Is the Nameplate and Why Does It Matter So Much?
The motor nameplate is mostly a metal/aluminum plate riveted or affixed to the motor frame. It carries, in a standard layout, manufacturer information, rated values and certification marks (such as CE). This plate is the motor's "identity" and the first reference for both ordering and commissioning.
From a buyer's standpoint, being able to read the nameplate is vital in three situations. First, when selecting a new motor, to determine the values suited to your application. Second, when replacing an existing motor, to find a one-to-one equivalent. Third, when commissioning, to set the correct connection and protection. In all three cases, correctly interpreting the nameplate values eliminates the risk of the wrong product and field incompatibility. We also covered ways to prevent the wrong motor in our article on nameplate matching.
Rated Power (kW / HP)
The most critical value on the nameplate is the motor's rated power, usually written in kW (some motors also show HP). This value is the mechanical output power the motor can deliver at the shaft, not the electrical power it draws. Our IE3 motors are offered in a wide power range of 0.55 kW – 355 kW. When ordering, you must correctly determine the power needed for your machine or pump: too little power strains the motor, while too much leads to running at an inefficient load point. We explained the conversion between HP and kW and understanding power correctly in our article on HP or kW.
Speed (rpm) and Poles
The value written as rpm on the nameplate is the motor's actual rotation speed at rated load. This speed depends on the pole count: a 2-pole motor runs ~3000 rpm, a 4-pole ~1500 rpm, a 6-pole ~1000 rpm. Values like 1440 or 2880 you see on the nameplate are slightly below synchronous speed due to slip; this is normal. We explained why slip pulls the actual speed below 1500 in our article on slip and actual speed. Speed should be chosen according to the speed the application requires; we addressed whether to choose 2 or 4 poles in our article on pole selection.
Rated Voltage and Connection (V / Δ / Y)
Voltage values on the nameplate are usually given in two forms: for example 230/400V or 400/690V. This shows which voltages the motor will run on in star (Y) and delta (Δ) connection. A standard three-phase IE3 motor is mostly connected in delta at 400V and in star at 690V. Your grid voltage must match the nameplate and the correct connection must be made; wrong wiring can burn out the motor. We examined when star-delta connection is needed for starting in our article on star-delta or soft starter.
Rated Current (A)
The rated current is the current the motor draws at full load, usually given next to the relevant voltage value. This value is critical for correctly selecting the motor protection relay (thermal), the contactor and the cable cross-section. Knowing the current correctly ensures the panel and protection equipment are sized correctly. We listed the protection equipment to request with the motor in our article on protection equipment. The nameplate may also state the start current / rated current ratio (Is/In); this ratio matters in generator and starting method selection.
Power Factor (cos φ)
The power factor (cos φ) shows how much of the apparent power the motor draws is converted into real work. The closer to 1, the better. A low power factor means more reactive power is drawn from the grid and can lead to a reactive energy penalty. IE3 and higher-efficiency motors generally run with a better power factor. We addressed the relationship between power factor and reactive penalty in our article on power factor and reactive penalty. From a buying standpoint, a motor with a low power factor can bring a hidden cost on the bill side.
Efficiency and Efficiency Class (IE3, % η)
The nameplate carries the IE3 marking and the efficiency percentage at certain load points (e.g. something like 88.6%). IE3 Premium is the efficiency class mandatory in many power bands under Turkish and EU regulation. Efficiency directly determines the energy cost over the motor's lifetime; high efficiency means significant savings in the long run. We gave which power requires which efficiency class as a table in our article on efficiency class mandate. We compared the decision between IE3 and the higher IE4 class with payback in our article on IE3 vs IE4.
Protection Class (IP) and Insulation Class (F/H)
The IP code on the nameplate (e.g. IP55) shows the motor's degree of protection against dust and water. Our standard IE3 production is made with IP55 protection; this is safe for dusty environments and those exposed to water splashes. Higher IP classes can be requested for harsher environments.
The insulation class (usually with the letter F or H) indicates the maximum temperature the winding can withstand. F class is standard, H class offers higher temperature resistance. On motors operating in hot environments or under high load, the insulation class directly affects life. We detailed the effect of insulation class on life and durability in our article on F/H insulation class.
Service Factor (SF)
The service factor (SF) shows how much the motor can be briefly overloaded above its rated power. For example, a motor with SF 1.15 can run 15% above its rated power for short periods. In applications with load fluctuation, a high service factor provides a safety margin. But the SF should not be seen as an excuse for continuous overload; if the motor is run above SF for long periods, it heats up and its life shortens. When buying, sharing the service factor suited to your application's load profile with us makes the right choice easier.
Duty Type (S1) and Frame/Mounting Information
The duty type on the nameplate indicates how the motor will operate. The most common, S1, denotes continuous operation; there are different duty types for intermittent applications. The nameplate also carries frame size (e.g. 132M) and mounting type (B3, B5, B35) information. This information is critical for mechanical compatibility: you can find frame size and power matching in our article on frame size and power matching, and mounting types on our mounting types page.
Frequency (Hz), Insulation and Temperature Rise
The nameplate carries a frequency value (50 Hz for Turkey and Europe). This is the grid frequency the motor is designed for and directly affects the speed calculation. If you will run the motor with a variable frequency drive (VFD), you should know the drive will run the motor at different frequencies, which changes the speed-torque relationship. We explained when a VFD is needed in our article on VFD with asynchronous motor.
Some nameplates also state the temperature rise class; for example, a motor with F insulation operating at B-class rise is longer-lived thanks to its lower operating temperature. This is an important quality when selecting motors for hot and dusty environments; we addressed this topic in detail in our article on motors in hot and dusty environments. We also examined using PT100 or a thermistor to monitor winding temperature in our article on temperature monitoring.
One-to-One Replacement with Nameplate Data
If you are replacing an existing motor, providing these nameplate values completely lets us find a one-to-one compatible equivalent even if the brand differs. Thanks to standard IEC dimensions, it is possible to choose an equivalent motor with the right power, speed, voltage, frame and mounting type. We explained nameplate matching step by step to prevent the wrong motor in our article on nameplate matching.
What to Note from the Nameplate Before Ordering: A Quick Checklist
To put nameplate reading into practice, note these values completely before ordering or replacing a motor: rated power (kW), speed (rpm) or pole count, rated voltage and connection (e.g. 400/690V), rated current (A), frequency (Hz), power factor (cos φ), efficiency class (IE3) and efficiency percentage, protection class (IP), insulation class (F/H), service factor (SF), duty type (S1), frame size and mounting type (B3/B5/B35), shaft diameter.
When you provide this list completely, we can offer a one-to-one compatible motor regardless of brand. Frame size, shaft diameter and mounting type are especially critical for mechanical compatibility; if these three do not match, the motor will not fit in the field. We explained the role of shaft diameter and key dimensions in coupling-pulley fit in our article on shaft diameter and key dimensions. We addressed the route to replacing an old brand one-to-one in our article on replacing an old brand motor.
Frequently Asked Questions
The nameplate has no kW, only HP. What should I do?
On some motors, power is given in HP (horsepower). 1 HP corresponds to about 0.75 kW. When ordering, doing this conversion correctly and stating the kW equivalent prevents a motor of the wrong power arriving. If you are unsure, simply share a photo of the nameplate with us; we will determine the correct kW equivalent together.
What do two voltage values (e.g. 400/690V) mean on the nameplate?
These two values show the voltages at which the motor will run in delta (Δ) and star (Y) connection. A 400/690V motor is connected in delta on a 400V grid and in star at 690V. The correct connection must be made according to your grid voltage. Wrong wiring damages the motor, so this value must be checked at commissioning.
If the nameplate is unreadable, how do I match the motor?
If the nameplate is erased or unreadable, we can determine an equivalent according to IEC standards from the existing motor's connection dimensions (frame size, shaft diameter, foot/flange dimensions) and the power the machine draws. Sharing the dimensions and application with us is enough for us to find the right equivalent.
Get a Quote
If you are having trouble reading the nameplate of your IE3 motor or are selecting a new motor, share your nameplate data with us; let us quickly determine the right motor for you with the correct power, speed, voltage and mounting type. As HEM Motor, a manufacturer and supplier, we offer the right product with stock and lead time. Call us now at +90 (532) 345 49 86 or send your request via our contact page. You can review our full IE3 motor range and product portfolio.
