YR Series Low-Voltage Three-Phase Asynchronous Motor

1 Overview

The YR315–355 (IP23) series of small, low-voltage, three-phase asynchronous motors represents a newly designed product line from our company. Featuring an attractive appearance and modern styling, these motors boast technical and economic performance indicators that meet advanced international standards. They are currently in mass production and are widely exported to over 20 countries and regions—including Europe, the Americas, Africa, Hong Kong, and Macau—as well as distributed throughout China, earning high acclaim from users.

Manufactured with high-quality materials and precision craftsmanship, this series offers numerous advantages, including high efficiency and energy savings, low noise and vibration, reliable operation, and ease of installation and maintenance.

The power ratings, electrical performance, mounting dimensions, and tolerances of this series comply with the national standard GB 755 (*Rotating Electrical Machines – Rating and Performance*), the International Electrotechnical Commission standard IEC 34-1 (*Rotating Electrical Machines – Rating and Performance*), and machinery industry standards JB 5272-91 and JB 5269-91.

The enclosure protection class for this series is IP23, in accordance with GB 4942.1 and IEC 34-5 (*Degrees of Protection Provided by the Enclosure of Rotating Electrical Machines*).

The cooling method for this series is IC01, in accordance with GB/T 1993-93 and IEC 34-6 (*Methods of Cooling for Rotating Electrical Machines*).

The construction and mounting arrangements include IMB3 (horizontal with feet, no flange on end shield) and IMV1 (shaft extension facing down, flange on bottom end shield), complying with GB 997 and IEC 34-7 (*Classification of Types of Construction and Mounting Arrangements of Rotating Electrical Machines*).

The tables in this catalog list the technical data and mounting dimensions for 380V-class motor specifications; derivative models for 440V, 660V, and other voltage classes are also available.

2 Scope of Application

This series of electric motors is suitable for driving various general-purpose machinery—such as compressors, fans, water pumps, machine tools, and transport equipment—serving as prime movers in industrial and mining enterprises across sectors like mining, machinery manufacturing, petrochemicals, and power generation. For motors driving equipment with high inertia—such as blowers, coal mills, rolling mills, hoists, crushers, and belt conveyors—relevant technical data must be provided and a technical agreement signed at the time of ordering; this information serves as the basis for the motor's specialized design to ensure reliable operation.

The YR (IP23) series motors are capable of delivering high starting torque with relatively low starting current and allow for speed regulation within a certain range. They are widely used in applications requiring: (1) higher starting torque than that provided by squirrel-cage motors; (2) operation where power supply line capacity is insufficient to start squirrel-cage motors; (3) long starting times or frequent starting; (4) speed regulation within a limited range; or (5) synchronized rotation via an "electric shaft" connection. Typical applications include compressors, presses, hoists, wire-drawing machines, conveyors, and printing presses.

Basic conditions for normal motor operation:

a Altitude not exceeding 1,000 m;

b Maximum ambient air temperature not exceeding 40°C; minimum ambient air temperature of -15°C;

c Monthly average maximum relative humidity of 90% during the most humid month, provided the monthly average minimum temperature does not exceed 25°C;

d Power supply frequency of 50 Hz ±1%;

e Operating voltage fluctuation within ±5% of the rated voltage;

f Motor duty type: continuous duty (S1);

3 Model Designation

The motor model designation is composed of two parts arranged in sequence—the product code and the specification code—in accordance with GB4831. The product code represents the motor series, with the following meanings:

Y —— Squirrel-cage rotor three-phase asynchronous motor

YR—— Wound-rotor three-phase asynchronous motor

The specification code consists of the shaft height, the core length sequence number, and the number of poles.

Example:

4 Structural Description

The motor frame and end shields are constructed from high-strength cast iron, and the stator utilizes an external press-fit structure. For motors with shaft heights of 315 and 355, the stator windings employ either pre-formed rigid coils made of rectangular copper wire or soft coils made of round copper wire; Class B or F insulation materials are used. The winding end turns are secured using a specialized, robust, and reliable lashing process. The entire stator undergoes Vacuum Pressure Impregnation (VPI) with Class F solvent-free varnish, ensuring excellent, reliable insulation performance as well as superior moisture and impact resistance.

Motors in this series feature reliable cast-aluminum squirrel-cage rotors; wound rotors utilize Class F insulation materials and undergo VPI treatment with Class F solvent-free varnish.

Rolling bearings are used, and the enclosure protection rating is IP23.

Motors with shaft heights of 315–355 are equipped with on-the-run grease replenishment and drainage devices, allowing for lubrication maintenance without stopping the motor.

The main terminal box features a sealed design with an IP54 protection rating. It is typically mounted on the right side of the motor (viewed from the shaft extension end) but can be mounted on the left side upon customer request. A dedicated grounding terminal is provided inside the terminal box.

5 Starting of Squirrel-Cage Induction Motors (Y Series)

Advanced computational techniques are employed to calculate the starting temperature rise and stress of the squirrel-cage rotors, thereby preventing premature motor failure caused by excessive starting loads. Users are advised to verify the following: (1) The moment of inertia of the driven equipment's rotating parts (referred to the motor speed) must not exceed the value specified for "Load J" in the technical data table; (2) The user's power grid must ensure that the voltage at the motor terminals during startup remains no lower than 85% of the rated voltage; (3) The load torque characteristics of the driven machinery must correspond to those of water pumps or fans.

Under the conditions above, the motor is permitted to undergo two consecutive starts from a cold state (with the motor coasting to a natural stop between starts) or one start from a hot state. Any subsequent start exceeding these limits must only be attempted after the motor has been stopped for one hour.

If the moment of inertia of the driven machinery's rotating parts exceeds the "Load J" value in the technical data table, or if frequent starting or heavy-load starting is required, please consult our company in advance. We will provide a special design to ensure reliable motor startup.

6 Ordering Instructions

Please indicate the following when ordering:

(1) Motor model: (Y355M1-6)

(2) Rated frequency: (50Hz)

(3) Rated power: (185kW)

(4) Rated voltage: (380)

(5) Number of poles: (6 poles)

(6) Protection level: (IP23)

(7) Cooling method: (IC01)

(8) Installation type: (IMB3)

(9) Direction of rotation: (clockwise [looking at the motor shaft extension end])

(10) Outlet box location: (right side of the motor [looking at the motor shaft extension end])

7 things to note

1. To check the moment of inertia of the driven mechanical equipment (after conversion to the rotational speed of the motor), please refer to the aforementioned Chapter 5: Starting of Squirrel Cage Motor;

2. If there are changes in working conditions or other special requirements, a separate technical agreement must be signed before the goods contract can be signed;

3. The technical performance data listed in the table in the sample are design values, which are close to the actual values. They are for reference when designing, selecting and ordering, but cannot be used as assessment standards. The standards for assessing motors are based on the corresponding technical conditions;

4. With the advancement of technology and the modification of relevant domestic and foreign standards, the technical data and dimensions in the sample are subject to change without further notice. Please request the official outline drawing from our company after ordering.