GB/T 755-2019

Rotating electrical machines—Rating and performance (English Version)

Standard No.

GB/T 755-2019

Language

Chinese, Available in English version

Release Date

2019

Published By

General Administration of Quality Supervision, Inspection and Quarantine of the People‘s Republic of China

Latest

GB/T 755-2019

Replace

GB/T 755-2008

Scope

This standard applies to all rotating electrical machines, except motors specified by other national standards and IEC standards, such as IEC60349. Motors within the scope of this standard may also comply with the requirements of other national standards and IEC standards that have been replaced, modified or supplemented, such as IEC60079 and IEC60092. Note: If certain provisions of this standard need to be modified in order to be suitable for special purposes such as radiation-tolerant motors or aerospace motors, all other provisions will remain valid as long as they are applicable.

Introduction

Core revisions to the standard

Technical parameters	GB/T755-2008	GB/T755-2019	Significance of revision
Thermal stability conditions	Change in 1 hour ≤2K	Change in half an hour ≤1K	Improve temperature control accuracy requirements
Insulation level	Up to 180(N)	New 200(N) level	Adapt to high temperature working conditions
Variable frequency motor	No explicit requirements	Mandatory IVIC marking	Regulated variable frequency drive system

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Key term analysis

3.25 Thermal stability

The new standard clearly defines it as: the state where the temperature rise of the motor heating component does not exceed 1K in half an hour, which is significantly higher than the 2008 version requirement of 2K per hour. Typical application case: Large synchronous generators need to be equipped with more sensitive temperature monitoring systems.

3.33 Runaway speed

A new term, referring to the maximum speed of the generator set after unloading when the speed governor fails. For example, hydro-turbine generators need to consider the mechanical strength of this working condition in their design.

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Technology Evolution Analysis

Insulation System Upgrade

The temperature rise limit values in Table 8 are adjusted to reflect the progress of material technology:

• The temperature rise of Class B insulation winding is reduced from 80K to 70K
• The new Class 200(N) insulation allows a temperature rise of 180K

Inverter compatibility requirements

New additions to Clause 7.1:

1. Must meet the IEC60034-18-41 no partial discharge requirements
2. Mandatory marking of IVIC (inverter compatibility level)

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Implementation Recommendations

Design Phase

For inverter drive motors:

• Use PDIV (partial discharge inception voltage) test to verify the insulation system
• Define CCC converter wiring code according to Table 3

Test verification

Notes on thermal performance test:

1. Use infrared thermal imager to monitor the temperature rise gradient for half an hour
2. For steam turbine generators> of >10MVA, special requirements in Table 4 must be followed