YE4 High-Efficiency Three-Phase Asynchronous Motor
As the technical team of Shaanxi Lite Simo Motor Co., Ltd., we have long been providing customers with selection guidance, delivery support, and on-site commissioning services for high-efficiency three-phase asynchronous motors. The YE4 series, as one of today’s most commonly used high-efficiency motor families, is widely applied in fans, pumps, compressors, and general machinery thanks to its reliable structural design and excellent operating performance.
In this article, drawing on hands-on field experience, I will provide a practical guide for site engineers that covers YE4 motor winding identification and terminal connections, the principles and implementation of delta (Δ) and star (Y) connections, key installation and commissioning precautions, and how to read essential technical information—while also explaining how our company supports customers throughout these stages.
I. Understanding Winding Identification and the Terminal Block
The stator windings of the YE4 series are typically identified by the letters U, V, W (sometimes A, B, C). Each phase winding has a start and an end marked at the terminal block (e.g., U1/U2, V1/V2, W1/W2).
It is important to note that the terminal arrangement is not necessarily a straight, phase-by-phase “start-to-end” layout. Instead, terminals are often arranged in a staggered pattern to facilitate bridging with connection links. This design is not intended to confuse users, but to improve manufacturing and wiring convenience. Understanding this helps site personnel quickly determine the correct connection method when encountering different manufacturers or frame sizes, and prevents wiring errors that could cause incorrect phase sequence or connection type.
II. Principles and Practical Implementation of Δ (Delta) and Y (Star) Connections
In engineering applications, three-phase asynchronous motors are commonly connected in either delta (Δ) or star (Y) configuration. Their basic differences are as follows:
Delta (Δ) connection:
Each phase winding is connected end-to-start to form a closed triangular circuit. This configuration is suitable for operation at rated line voltage and can deliver higher torque. It is commonly used where full-load or high-torque output is required at rated voltage. In practice, shorting links are used on the terminal block to bridge one terminal of each phase to the corresponding terminal of the next phase, completing the delta loop.
Star (Y) connection:
One end of each phase winding is connected together to form a neutral point, while the other ends are connected to the power supply. The effective phase voltage is reduced to line voltage divided by √3, making this configuration suitable for applications sensitive to starting voltage or where reduced starting current is required. In practice, connecting the three starts or the three ends together with horizontal links completes the star connection.
What matters more than memorizing terminal positions is understanding the physical meaning of the bridging: regardless of how the terminals are arranged, correctly identifying which terminals belong to the same phase and shorting them according to delta or star principles is the key to proper wiring.
III. Key Installation and Commissioning Precautions (Our Practical Emphasis)
Based on frequent on-site experience, we highlight the following points for engineers and electricians:
Verify terminal markings: Before wiring, always confirm the markings U1, U2, V1, V2, W1, W2 against the motor nameplate or wiring diagram. Avoid blind connections.
Check phase sequence: Before first energization, use a phase-sequence tester or perform a low-load trial run to confirm correct rotation. If the direction is incorrect, simply swap any two phase lines.
Select proper links and cables: Connection links and incoming conductors must be sized for the rated current. Bolts must be tightened securely with anti-loosening measures. Poor contact can create hot spots and shorten winding life.
Reliable grounding and protection: The motor frame must be properly grounded. Keep the terminal box clean and well insulated, and install appropriate overload, overcurrent, short-circuit, and grounding protection.
Mechanical alignment and coupling inspection: When installing the motor with the driven equipment, perform mechanical alignment first. Check coupling clearances and measure vibration and temperature rise under both no-load and load conditions.
Environment and cooling: Pay attention to the cooling method and installation location. Avoid blocked airflow, high ambient temperatures, or dusty environments. If necessary, select enhanced protection or improved cooling solutions.
Refer to nameplate and factory drawings: Terminal layouts may vary between manufacturers or even between different frame sizes of the same series. When in doubt, always follow the motor nameplate and factory wiring diagram.
IV. Common Misunderstandings and Our Recommendations
Many on-site issues are not caused by complex technical problems, but by carelessness or misunderstanding—for example, assuming terminals correspond linearly, ignoring the current-carrying capacity of links, or running the motor under load without checking phase sequence.
We recommend following a standard procedure for every installation:
verify nameplate → verify wiring diagram → no-load rotation and phase-sequence check → record temperature and vibration → load operation and observe protection response.
Whenever operating conditions change (such as voltage level or power supply method), the connection method and protection settings should be rechecked.
V. Key Technical Information to Review for the YE4 Series
When consulting product data or technical manuals, site personnel should focus on the following items: rated power; rated voltage/current; number of poles and speed; efficiency class; power factor; insulation class; cooling method (IC code); degree of protection (IP); installation dimensions (shaft extension, foot dimensions, coupling center height); and motor weight.
Dimensional and installation drawings are especially critical for alignment, foundation design, and cable routing. Upon delivery, our company provides detailed outline drawings and wiring diagrams. If special modifications are required—such as additional terminal boxes, improved cooling, or upgraded protection ratings—these can be discussed in advance for customization.
VI. Support Provided by Shaanxi Lite Simo Motor Co., Ltd.
As both manufacturer and service provider, we commit to the following support throughout the delivery and service life of YE4 products:
Comprehensive technical manuals and wiring diagrams
On-site installation and commissioning guidance, with technicians dispatched when necessary
Customized wiring and protection solutions for special operating conditions (e.g., parallel/series power supply, multi-motor coordinated starting schemes)
Readily available spare parts and maintenance training to help customers establish routine inspection and preventive maintenance programs
Rapid fault analysis advice and repair services in case of abnormalities such as overheating, excessive vibration, or signs of inter-turn winding faults
Principles First, Standards Always
Understanding high-efficiency three-phase asynchronous motors such as the YE4 series should not be limited to memorizing where a link is placed for delta or star connection. Instead, it should start from winding identification, phase-sequence principles, and the function of bridging links. Only by mastering the fundamentals and combining them with specific frame sizes and terminal layouts can on-site wiring and commissioning be completed quickly and accurately.
Shaanxi Lite Simo Motor Co., Ltd. is committed to being your long-term technical partner, providing reliable support and attentive on-site service for every motor selection, wiring task, and maintenance operation. If you require detailed parameter tables, outline drawings, or wiring diagrams for specific frame sizes (such as 280–355) and applications, please provide the model and operating conditions—we will promptly supply complete documentation and arrange technical coordination.
