NEMA及IEC标准下的电机铭牌识别（连载二）

国际电工委员会 (IEC) 是与北美国家电气制造商协会 (NEMA) 标准的国际对应机构。

NEMA 和 IEC 标准使用不同的术语，但它们在额定值方面基本相似，并且在大多数常见应用中可以互换。简而言之，NEMA 标准往往更为保守，而 IEC 标准则更为精确、具体且分类更清晰。

现在了解了 NEMA 电机术语，下面将介绍 IEC 最常见的名称及其与 NEMA 标准的关系。

The International Electrotechnical Commission (IEC) is the international counterpart to the North American- National Electrical Manufacturers Association (NEMA) standards.

The NEMA and IEC standards use different terms, but they are essentially analogous in ratings and, for most common applications, are largely interchangeable. In brief NEMA standards tend to be more conservative while IEC standards tend to be more precise, specific and more categorized.

Now that we understand the NEMA motor terminology, here’s a primer on the most common designations of IEC and how they relate to NEMA standards.

框架关系

Frame relationships

IEC 和 NEMA 电机都使用字母代码来指定物理框架尺寸，但代码不同。

IEC 电机的机座号由两部分字母/数字代码组成。代码的字母部分指定物理框架尺寸，而数字部分指定通用框架尺寸。

字母部分可能比较复杂，例如，IEC 电机的“K”代码相当于 NEMA 电机的“H”，而 IEC 电机的“H”代码相当于 NEMA 电机的“D”。

代码的数字部分（表示机座尺寸）比较容易混淆，重叠部分也较少；例如，IEC 的“56”适用于亚分功率电机，而 NEMA 的“56”适用于 ¼ - 1.5 HP 电机。

IEC 还通过代码定义电机的安装位置和连接法兰类型。一些较常见的安装位置代码包括 B3（代表底脚安装）和 B5（代表无底脚安装）。IEC 定义了三种不同的法兰类型：FF、FT 和 FI 法兰。FF 法兰带有通孔螺栓孔，适用于 56 至 280 的机架尺寸。FT 法兰带有螺纹螺栓孔，也适用于 56 至 280 的框架尺寸。

请注意，所有 IEC 尺寸均为公制单位。

Both IEC and NEMA motors use a letter code to specify the physical frame dimensions, but the codes are different.

The frame designation for IEC motors is composed of a two-part letter/number code. The letter portion of the code specifies the physical frame dimensions, while the number portion of the code specifies the general frame size.

The letters can get especially tricky, for example, a "K" code for an IEC motor is equivalent to a NEMA "H", whereas an IEC "H" is equivalent to a NEMA "D".

The numeric portion of the code (indicating frame size) is less confusing and there is less overlap; for instance an IEC "56" is for sub-fractional motors whereas a NEMA "56 is from ¼ - 1.5 HP motors).

The IEC also defines a motor's mounting position and connecting flange type by a code. A couple of the more common mounting position codes include B3 for foot mounted and B5 for footless. Three different flange types are defined: FF, FT and FI flanges. The FF flange has through bolt holes, and is available for frame sizes from 56 to 280. The FT flange has threaded bolt holes and is also available for frame sizes from 56 to 280.

Note that all the IEC dimensions are in metric units.

外壳标识

Enclosure designations

与 NEMA 类似，IEC 也使用标识来指示电机外壳提供的防护等级。然而，当 NEMA 标识以文字形式出现时，例如“开放式防滴漏”或“全封闭式风扇冷却”，IEC 则使用两位数的“防护等级”代码来描述外壳保护电机免受环境影响的程度。第一位数字表示电机防止固体物体进入的防护等级，第二位数字表示防止水进入的防护等级。两位数字前面带有字母“IP”。

第一位数字的含义如下：

0 - 无防护

1 - 可防止直径大于 50 毫米（约 2 英寸）的物体进入，例如手

2 - 可防止直径大于 12 毫米（约 1/2 英寸）的物体进入，例如手指

4 - 可防止直径大于 1 毫米（约 0.04 英寸）的物体进入，例如小型工具和电线

5 - 全面防护，包括防尘。

第二位数字表示防水等级。具体等级如下：

0 - 无防护

1 - 可防止垂直落水

2 - 可防止与垂直方向成 15 度角的落水

3 - 可防止与垂直方向成 60 度角的喷水

4 - 可防止来自任何方向的溅水

5 - 可防止来自各个方向的喷射水流

6 - 可防止波涛汹涌的海水

7 - 可防止浸入深度在 0.15 至 1.0 米之间的水深

8 - 可防止长时间浸入深水

总体而言，NEMA 的标识更具描述性和通用性，而 IEC 的 IP 代码则更精确，定义更狭窄。对于大多数工业应用，IP 22 指的是开放式防滴电机，IP44 或 IP54 指的是全封闭式电机，IP45 指的是防风雨电机，IP55 指的是可冲洗电机。对于防爆电机，国家电气规范定义的危险环境与 IEC“防火”电机的危险环境相同。

Like NEMA, IEC has designations indicating the protection provided by a motor's enclosure. However, where NEMA designations are in words, such as Open Drip Proof or Totally Enclosed Fan Cooled, the IEC uses a two-digit "Index of Protection" code to describe how well the enclosure protects the motor from the environment. The first digit indicates how well protected the motor is against the entry of solid objects, the second digit refers to water entry. The two digit number is preceded by the letters “IP”.

Here's what the first digit means:

0 - No protection

1 - Protection against objects larger than 50mm (about 2 in.) in diameter, like hands

2 - Protection against objects larger than 12mm (about 1/2 in.) in diameter, like fingers

4 - Protection against objects larger than 1mm (about 0.04 in.) in diameter, like small tools and wires

5 - Complete protection, including dust-tightness.

The second digit signifies protection against water entry. Here are those ratings:

0 - No protection

1 - Protected from water falling straight down

2 - Protected from water falling as much as 15 deg from vertical

3 - Protected from spraying water as much as 60 deg from the vertical

4 - Protected from splashing water coming from any direction

5 - Protected against jets of water from all directions

6 - Protected from heavy seas

7 - Protected against the effects of immersion to depths of between 0.15 and 1.0 m

8 - Protected against the effects of prolonged immersion at depth

By way of general comparison, the NEMA designations are more descriptive and general, whereas the IEC IP codes are more precise and narrowly defined. For most industrial application, an IP 22 relates to open drip-proof motors, IP44 or IP54 to totally enclosed, IP45 to weatherproof, and IP55 to wash-down duty motors. For explosion proof motors, the hazardous atmospheres defined by national electrical code parallel those of the IEC "flame-proof" motors.

冷却标识

Cooling designations

同样，IEC 使用字母和数字组成的 IC 代码来表示电机的冷却方式。几乎每种冷却方式都有单独的代码，从小型风冷电机到大型液冷电机。代码可能非常复杂，最多包含四个字母和四位数字。

以下列出了一些较常见的“短代码”：

IC 01 - 第一位数字表示空气可以自由进出电机。第二位数字表示气流由内置风扇或“自感应”产生。由于内部风扇的作用，这对应于标准的 NEMA 开放式风冷电机。

IC 40 - 第一位数字表示框架表面（外壳）已冷却（即无内部气流）。第二位数字表示仅通过对流冷却，无风扇作用。这对应于 NEMA 全封闭、无通风 (TENV) 电机。

IC 41 - 第一位数字同样表示框架表面冷却，但第二位数字表示电机气流由内置风扇引起。这对应于 NEMA 全封闭风冷 (TEFC) 电机。

IC 48 - 第一位数字表示外部框架/外壳表面已冷却（即无内部气流）。但第二位数字表示电机处于驱动风扇或鼓风机的气流中。这对应于 NEMA 全封闭风冷电机 (TEAO)。这适用于电机处于其驱动的风扇或鼓风机的气流中，从而通过风扇作用进行冷却的用途。

因此，在大多数实际应用中，IC 01 代表 NEMA 开放式设计，IC 40 代表全封闭无通风 (TENV)，IC 41 代表全封闭风冷 (TEFC)，IC 48 代表全封闭风冷 (TEAO)。

Again, IEC uses a letter and number IC code to designate how a motor is cooled. There is an individual code for just about every type of cooling method, from small fan cooled motors to large liquid cooled motors. The code can get quite complex; up to a four-letter and four-digit code.

A few of the more common “short codes" are shown below:

IC 01- The first digit indicates that the air can flow freely in and out of the motor. The second digit indicates that the airflow is caused by an integral fan, or "self-induced". This corresponds to a standard NEMA open fan-cooled motor because of the internal-fan action.

IC 40 - The first digit means the frame surface (external enclosure) is cooled (i.e. no internal flow). The second digit indicates that cooling by convection only without a fan action. This corresponds to a NEMA totally enclosed, non-vented (TENV) motor.

IC 41 - The first digit again indicates frame-surface cooling, but the second indicates that airflow over the motor is caused by an integral fan. This corresponds to a NEMA Totally-Enclosed FanCooled (TEFC) motor.

IC 48 - The first digit indicates that the external frame/enclosure surface is cooled (i.e., no internal flow). But the second says that the motor is in the air stream of the driven fan or blower. This corresponds to a NEMA Totally Enclosed, Air-Over motor (TEAO). This relates to uses where the motor is in the air stream of the fan or blower it drives, and is thus cooled by fan action.

Thus for most practical purposes, IC 01 relates to a NEMA open design, IC 40 Totally Enclosed Non-Ventilated (TENV), IC 41 to Totally Enclosed Fan Cooled (TEFC), and IC 48 to Totally Enclosed Air Over (TEAO).

占空比

Duty Cycles

NEMA 电机以两个或三个术语之一来表示占空比：连续、间歇或特殊负载（通常以分钟表示）。IEC 将其分为八个等级：

S1 - 连续工作模式：电机以恒定负载运行足够长的时间以达到温度平衡。

S2 - 短时工作模式：电机以恒定负载运行，但运行时间不足以达到温度平衡，而停机时间足够长，使电机达到环境温度。

S3 - 间歇周期工作模式：在恒定负载下，以顺序、相同的运行和停机周期运行。永远不会达到温度平衡。启动电流对温升影响很小。

S4 - 带启动的间歇周期工作模式：在恒定负载下，以顺序、相同的启动、运行和停机周期运行。不会达到温度平衡，但启动电流会影响温升。

S5 - 间歇式周期运行，带电制动：以相同的顺序循环启动、恒载运行和空载运行。无停机时间。

S6 - 间歇式负载连续运行：以相同的顺序循环启动、恒载运行和空载运行。无停机时间。

S7 - 连续运行，带电制动：以相同的顺序循环启动、恒载运行和电制动。无停机时间。

S8 - 负载和速度周期性变化的连续运行：以相同的顺序循环运行，先以恒定负载和给定速度运行，然后以其他恒定负载和速度运行。无停机时间。

The NEMA motors refer to duty cycle in one of two or three terms: continuous, intermittent or special duty (typically expressed in minutes). IEC breaks it into eight ratings:

S1 - Continuous duty: The motor works at a constant load for enough time to reach temperature equilibrium.

S2 - Short-time duty: The motor works at a constant load, but not long enough to reach temperature equilibrium, and the rest periods are long enough for the motor to reach ambient temperature.

S3 - Intermittent periodic duty: Sequential, identical run and rest cycles with constant load. Temperature equilibrium is never reached. Starting current has little effect on temperature rise.

S4 - Intermittent periodic duty with starting: Sequential, identical start, run and rest cycles with constant load. Temperature equilibrium is not reached, but starting current affects temperature rise.

S5 - Intermittent periodic duty with electric braking: Sequential, identical cycles of starting, running at constant load and running with no load. No rest periods.

S6 - Continuous operation with intermittent load: Sequential, identical cycles of running with constant load and running with no load. No rest periods.

S7 - Continuous operation with electric braking: Sequential identical cycles of starting, running at constant load and electric braking. No rest periods.

S8 - Continuous operation with periodic changes in load and speed: Sequential, identical duty cycles run at constant load and given speed, and then run at other constant loads and speeds. No rest periods.

设计类型

Design Types

IEC 设计额定值代码描述了电机的转速与扭矩特性。IEC 设计代码与 NEMA 设计类型几乎相同，只是字母不同。例如，最常见的工业电机是 IEC 设计 N 电机，它与 NEMA 设计 B 电机非常相似；后者是工业应用中最常见的电机类型。同样，IEC 设计 H 的特性与 NEMA 设计 C 的特性几乎相同。没有与 NEMA 设计 D 对应的特定 IEC 型号。

从逻辑上讲，IEC 后缀是有含义的。例如，IEC 设计 N（可视为“正常”扭矩）电机的扭矩通常与 NEMA 设计 B 电机的扭矩相同。IEC 设计 H（可视为“高”扭矩）的扭矩与 NEMA 设计 C 的扭矩几乎相同。

The IEC design rating code describes a motor's speed vs. torque characteristics. The IEC Design codes nearly mirror NEMA Design Types, but with different letters. For example, the most common industrial motor is an IEC Design N motor, which is very similar to a NEMA Design B motor; the most common type of motor for industrial applications. By the same token, the characteristics of IEC Design H are nearly identical to those of NEMA Design C. There is no specific IEC equivalent to NEMA Design D.

Logically the suffix with IEC has a meaning. Say comparing toques of IEC Design N (think of it as "normal" torque) motors in general mirror those of NEMA Design B motors. The torque of IEC Design H (think of it as "high" torque) is nearly identical to those of NEMA Design C.

绝缘标志

Insulation designations

IEC 和 NEMA 使用相同的绕组绝缘分类系统。该系统基于材料在不降低或缩短电机寿命的情况下能够持续承受的最高温度。下表比较了 IEC 和 NEMA 标准允许的温升（总可接受温度需加 45°C）。

*请注意，NEMA 没有 E 级。

大多数工业电机根据应用情况使用 B 级或 F 级绝缘。IEC 和 NEMA 1.00 的服务系数额定值几乎相同；NEMA 1.15 的额定值更高。

IEC and NEMA use the same classification system for winding insulation. It is based on the highest temperature the material can withstand continuously without degrading or reducing motor life. The table below compares temperature rises (add 45°C for total acceptable temperature) allowed under IEC and NEMA standards.

*Note that NEMA has no Class E.

Most industrial-duty motors use Class B or Class F insulation, depending on the application. IEC and NEMA 1.00 service factor ratings are nearly identical; NEMA 1.15 ratings are higher.

千瓦和马力

Kilowatts & horsepower

这是额定电压、电流和频率下的额定轴功率输出。IEC 使用千瓦 (kW)，NEMA 使用马力 (hp)。两者之间的换算关系为 1hp = 745.7 W = 0.7457kW。

与 NEMA 一样，IEC 也为标准机座号分配相应的功率额定值。

在较小的额定值下，IEC 和 NEMA 的千瓦/马力比较结果比较流畅，但在较大的机座号下，它们的差异可能会大到在某些设计应用中引起担忧。例如，IEC 115S/NEMA364T 区域适用于 4 极电机。其中，NEMA 要求机座号的功率为 75 hp，而 IEC 要求的功率为 50 hp。如果尺寸差异可以接受，则降至 NEMA 326T 机座号即可满足所需的 50 hp 功率。如果需要 364T 尺寸，请确保不要损坏传动系统或使用更大功率的电机负载。

This is the rated shaft power output at the rated voltage, current and frequency. IEC uses kilowatts (kW) and NEMA uses horsepower (hp). The conversion between the two is 1hp = 745.7 W = 0.7457kW

Like NEMA, IEC assigns comparable power ratings to standard frame sizes.

IEC and NEMA kW/hp comparisons flows smoothly in smaller ratings, but in larger sizes they can vary enough to cause concern in some design applications. An example is IEC 115S/NEMA364T areas for 4-pole motors. Here, NEMA calls for 75 hp in the frame size in which IEC calls for 50 hp. Dropping to a NEMA 326T frame provides the 50 hp needed if the dimensioning differences can be tolerated. If you need the 364T dimensions, be sure not to damage the drive train or load with the higher-power motor.

额定电压（伏特）

Rated Voltage (Volts)

IEC 34-1 标准要求电机能够在额定电压的 95% 至 105% 范围内以额定效率提供额定输出。

IEC standard 34-1 requires that motors be able to provide their rated output at their rated efficiency for a voltage range of 95% to 105% of the rated voltage.

效率

Efficiency

IEC 电机的效率通常以满载或 75% 负载表示。此外，电机上可能还会标明效率等级（EFF1、EFF2 和 EFF3）。

The efficiency for IEC motors is usually given at full load or at 75% load. Also, an efficiency rating (EFF1, EFF2, and EFF3) may appear on the motor.

服务系数（不适用于 IEC 电机）

Service Factor (not used for IEC motors)

IEC 电机没有“服务系数”额定值定义。相反，温升、环境温度和海拔高度额定值是通过输出功率（kW）来定义的。如果需要更高的服务系数，请使用更大尺寸的电机。

IEC motors do not have a "Service Factor" rating definition. Instead, the temperature rise, ambient temperature and altitude ratings are defined via the kW output rating. If an increased service factor is required, use the next size larger motor.

这是铭牌术语和 IEC/NEMA 比较的简要指南。IEC 额定值通常比 NEMA 更符合逻辑、更系统、更具描述性。

摘要

随着市场日益全球化，电机铭牌的通用语言将使电气工程师/技术人员能够在新的选型、安装或更换过程中快速理解和识别他们所处理的电机类型。

虽然 NEMA 标准适用于北美市场，但世界其他地区遵循 IEC 标准。如果能够快速识别描述电机尺寸、转速、电压、物理尺寸和性能特征的关键项目，那么选择和更换电机就会变得容易得多。所有这些信息以及更多信息通常都可以在电机铭牌上找到。验证 NEMA 是否符合 IEC 或其他行业标准，能够在项目现场的任何位置正确使用电机。

通常，IEC 标准比 NEMA 标准精确得多，它定义了每种电机尺寸的耐久性和通断额定值。 NEMA 标准并不那么精确，而且采取了更为保守的方法。

That's a short guideline in nameplate terminology and IEC/NEMA comparisons. IEC rating’s in general follows a more logical, systematic, and descriptive path than those of NEMA.

Summary

As the markets continue to become more global, the common language of the motor nameplate will enable the electrical engineers/technicians to quickly understand and recognize exactly what type of motor they're dealing with during a new selection, installation or replacement procedure.

While NEMA standards are for the North American markets, the rest of the world follows the IEC standards. Selecting and replacing motors becomes a lot easier when you can quickly recognize the key items that describe a motor's size, speed, voltage, physical dimensions, and performance characteristics. All of this information and more is usually available on the motor's nameplate. Verifying conformance of NEMA to IEC or other industry standards would enable you to apply motors correctly anywhere on the project site.

In general, the IEC standards are much more precise than the NEMA standardsx, defining endurance and make/ break rating for each motor size. NEMA standards are not as precise and take on a more conservative approach.

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