GB/T 14048.16-2025Low-voltage switchgear and controlgear - Part 8: Control units for built-in thermal protection (PTC) for rotating electrical machines (English PDF)

Foreword

This document complies with the provisions of GB/T 1.1-2020 "Standardization Work Guidelines Part 1: Structure and Drafting Rules of Standardization Documents".

Drafting.

This document is Part 8 of GB/T 14048 "Low-voltage switchgear and controlgear". GB/T 14048 has published the following...

part.

---Part 1: General Provisions;

---Part 2: Circuit Breakers;

---Part 3: Switches, Isolators, Disconnecting Switches and Fuse Combinations;

---Part 4-1.Contactors and Motor Starters Electromechanical contactors and motor starters (including motor protectors);

---Part 4-2.Contactors and Motor Starters. Semiconductor Controllers and Starters (including Soft Starters) for AC Motors;

---Part 4-3.Contactors and Motor Starters. AC Semiconductor Controllers and Contactors for Non-Motor Loads;

---Part 5-1.Control Circuit Appliances and Switching Elements - Electromechanical Control Circuit Appliances;

---Part 5-2.Control Circuits, Electrical Appliances, and Switching Elements (Proximity Switches);

---Part 5-3.Control Circuitry and Switching Elements. Proximity Switches (PDDBs) with Defined Functionality under Fault Conditions Require;

---Part 5-4.Special Tests for Performance Evaluation of Small-Capacity Contacts in Control Circuits and Switching Elements;

---Part 5-5.Electrical emergency braking devices with mechanical latching function, including control circuitry and switching elements;

---Parts 5-6.Control Circuit Electrical Appliances and Switching Elements DC Interface for Proximity Sensors and Switching Amplifiers (NAMUR);

---Parts 5-7.Requirements for control circuit electrical appliances and switching elements for proximity devices with analog outputs;

---Parts 5-8.Control Circuit Electrical Appliances and Switching Elements - Three-position Enable Switch;

---Parts 5-9.Control Circuits, Electrical Appliances, and Switching Elements; Flow Switches;

---Part 6-1.Multifunctional Electrical Transfer Switches;

---Part 6-2.Multifunctional Electrical Appliances (Equipment) Control and Protection Switchgear (Equipment) (CPS);

---Part 7-1.Terminal blocks for copper conductors of auxiliary devices;

---Part 7-2.Protective conductor terminal blocks for copper conductors of auxiliary devices;

---Part 7-3.Safety requirements for auxiliary device fuse terminal blocks;

---Part 7-4.PCB terminal blocks for copper conductors of auxiliary components;

---Part 7-5.Terminal blocks for aluminum conductors in auxiliary components;

---Part 8: Built-in thermal protection (PTC) control unit for rotating electrical machines;

---Part 9-1.Arc-extinguishing devices for active arc fault suppression systems;

---Part 9-2.Active Arc Fault Suppression System. Internal Arc Detection and Suppression Device Based on Optical Signals.

This document replaces GB/T 14048.16-2016 "Low-voltage switchgear and controlgear - Part 8: In-line thermal insulation for rotating electrical machines".

Compared with GB/T 14048.16-2016, the main technical changes in the "PTC Control Unit" are as follows, except for structural adjustments and editorial modifications.

---Added requirements for energy-constrained circuits (see 8.1.14);

---The requirement for a disconnection detection function has been added (see 8.2.12);

---The appendix "Special Tests" is changed to "Additional Requirements and Tests for Electrical Appliances with Protective Isolation" (see Appendix B, 2016 edition).

Appendix B).

This document is modified to adopt IEC 60947-8:2021 "Low-voltage switchgear and controlgear - Part 8: In-situ thermal insulation for rotating electrical machines".

Protection (PTC) control unit.

The technical differences between this document and IEC 60947-8:2021, and the reasons therefor, are as follows.

---The IEC 60417 Database (see 8.1.1) has been replaced with the normatively referenced GB/T 5465.2 to adapt to my country's national conditions;

---IEC 60068-2-27 (see 8.2.10.1) has been replaced with the normatively referenced GB/T 2423.5 to adapt to my country's national conditions;

---IEC 60068-2-6 (see 8.2.10.2 and 9.3.3.14.3) has been replaced with the normatively referenced GB/T 2423.10 to adapt to my country's national standards.

National conditions;

---CISPR11.2015 and CISPR11.2015/AMD1.2016 have been replaced with the normatively referenced GB 4824-2025 (see GB 4824-2025).

(9.4.3.2, 9.4.3.3), to adapt to my country's national conditions.

The following editorial changes have been made to this document.

---In section 3.1.8, TNF is listed as a separate symbol on a separate line;

---In version 3.1.9, TFS is listed as a separate symbol on a separate line;

---In section 5.4.2, referring to the wording of IEC 60738-1:2022, "RNF" is changed to "R-TNF", that is, it is changed to "---resistance under TNF".

R-TNF (see Figure 2 of IEC 60738-1:2022, if applicable);

---In section 9.1.2, the number j) is missing between i) and k). Change k) to j), and adjust the subsequent numbers accordingly;

---In section 9.3.3.10, the last paragraph is item d), which should be changed to "The tests specified in d), b), and c) should be performed at the terminals where the PTC thermistor is pre-connected".

After connecting a 0.2µF capacitor between the terminals, the test is repeated. The resistance value at the disconnection point of the control unit is compared with the resistance value at the disconnection point of the previous test.

The resistance difference should not exceed 5%;

---The main text of the last paragraph in A.1 should be the content of Note 3.That is, change it to "Note 3.When the applied voltage is 2.5V and below..." (Except for the TNF 15K point, where the applied voltage is allowed to reach 7.5V), the above resistance values and corresponding operating characteristic tolerances that's correct. If the applied voltage exceeds the above value, the performance of the PTC thermistor and its control unit may not meet the requirements.

"Normal tolerance for motion characteristics";

---In section B.3.2, "directly connected to each" is changed to "directly grounded," that is, "for systems connected to a grounded neutral system or an impedance system." for the equipment, the neutral point of the main circuit of the test circuit should be directly grounded.

Please note that some content in this document may involve patents. The issuing organization of this document assumes no responsibility for identifying patents.

This document was proposed by the China Electrical Equipment Industry Association.

This document is under the jurisdiction of the National Technical Committee on Standardization of Low Voltage Electrical Appliances (SAC/TC189).

Introduction

Low-voltage switchgear and control equipment are produced in large quantities and are widely used, including circuit breakers, isolators, disconnect switches and fuse combinations, contactors, and...

Starters, etc., are widely used in various fields such as machinery, power, and electronics, involving multiple aspects of electrical energy control and distribution. GB/T 14048 "Low-voltage switchgear and controlgear" is an important series of standards guiding related products of low-voltage switchgear and controlgear in my country, and is proposed to be compiled by 25 ministries.

Composition.

---Part 1: General Provisions. This section aims to specify the general requirements for low-voltage switchgear and controlgear.

---Part 2: Circuit Breakers. This section specifies the performance requirements and test methods for circuit breakers, as well as other product-related requirements.

---Part 3: Switches, Isolators, Disconnecting Switches and Fuses Combinations. The purpose is to specify the components of switches, isolators, disconnecting switches, and fuses.

Product-related requirements, such as performance requirements and test methods for fuse combination electrical appliances.

---Part 4-1.Contactors and Motor Starters Electromechanical contactors and motor starters (including motor protectors).

The key is to specify the performance requirements and test methods for electromechanical contactors and motor starters (including motor protectors), etc.

Relevant requirements.

---Part 4-2.Contactors and Motor Starters Semiconductor Controllers and Starters (including Soft Starters) for AC Motors the purpose is to specify the performance requirements and test methods for semiconductor controllers and starters (including soft starters) for AC motors.

Product-related requirements.

---Part 4-3.Contactors and Motor Starters. AC Semiconductor Controllers and Contactors for Non-Motor Loads. The purpose is to...

The product-related requirements include performance requirements and test methods for AC semiconductor controllers and contactors used for non-motor loads.

---Part 5-1.Control Circuit Appliances and Switching Elements - Electromechanical Control Circuit Appliances. The purpose is to specify electromechanical control circuit appliances.

Product-related requirements, such as the performance requirements and testing methods for electrical circuit components.

---Part 5-2.Control Circuits, Electrical Appliances, and Switching Elements - Proximity Switches. The purpose is to specify the performance requirements and testing procedures for proximity switches.

Product-related requirements such as testing methods.

---Part 5-3.Requirements for proximity switches (PDDBs) that maintain their specified function under fault conditions, including control circuitry and switching elements.

The purpose is to specify the performance requirements and test methods for proximity switches that have a defined function under fault conditions, and other product-related requirements.

Require.

---Part 5-4.Special Tests for Performance Evaluation of Small-Capacity Contacts in Control Circuits and Switching Elements. The purpose is to...

Special test requirements are specified for the performance evaluation of small-capacity contacts.

---Part 5-5.Electrical emergency braking devices with mechanical latching function, including control circuitry and switching elements. The purpose is to...

The regulations specify the performance requirements and test methods for electrical emergency braking devices with mechanical latching functions, as well as other relevant product requirements.

---Parts 5-6.Control Circuit Electrical Appliances and Switching Elements DC Interface for Proximity Sensors and Switching Amplifiers (NAMUR) the purpose is to specify the performance requirements and test methods for the DC interfaces of proximity sensors and switching amplifiers, as well as other product-related requirements.

---Parts 5-7.Requirements for control circuit electrical appliances and switching elements used in proximity devices with analog outputs. The purpose is to specify...

Product-related requirements, such as performance requirements and test methods, for proximity devices with analog outputs.

---Parts 5-8.Control Circuit Electrical Appliances and Switching Elements - Three-position Enable Switch. The purpose is to specify the performance characteristics of three-position enable switches.

Product-related requirements, such as requirements and testing methods.

---Parts 5-9.Control Circuits, Electrical Appliances, and Switching Elements - Flow Switches. The purpose is to specify the performance requirements and testing procedures for flow switches.

Product-related requirements such as testing methods.

---Part 6-1.Multifunctional Electrical Transfer Switches. The purpose is to specify the performance requirements and test methods for transfer switches.

Requirements related to products such as [illegible]

---Part 6-2.Multifunctional Electrical Appliances (Equipment) - Control and Protection Switchgear (CPS). The purpose is to specify control and protection switching equipment.

Product-related requirements, such as performance requirements and test methods for protective switching devices.

---Part 7-1.Terminal blocks for copper conductors in auxiliary devices. The purpose is to specify the performance requirements of copper conductor terminal blocks.

Requirements and testing methods, etc., related to the product.

---Part 7-2.Protective Conductor Terminal Blocks for Auxiliary Devices' Copper Conductors. The purpose is to specify the protective conductor terminals for copper conductors.

Product-related requirements, such as performance requirements and test methods for terminal blocks.

---Part 7-3.Safety Requirements for Auxiliary Devices Fuse Terminal Blocks. The purpose is to specify the safety requirements for fuse terminal blocks.

Safety-related requirements.

---Part 7-4.PCB Terminal Blocks with Copper Conductors for Auxiliary Components. The purpose is to specify PCB terminal blocks with copper conductors.

Product-related requirements, such as performance requirements and testing methods.

---Part 7-5.Terminal blocks for aluminum conductors in auxiliary components. The purpose is to specify the performance requirements of terminal blocks for aluminum conductors.

Requirements and testing methods, etc., related to the product.

---Part 8: PTC (Positioned Thermal Protection) Control Units for Rotating Electrical Machines. The purpose is to specify the PTC control units for rotating electrical machines.

Product-related requirements, such as performance requirements and test methods for the protection (PTC) control unit.

---Part 9-1.Arc-extinguishing devices for active arc fault suppression systems. The purpose is to specify the performance requirements and testing procedures for arc-extinguishing devices.

Product-related requirements such as methods.

---Part 9-2.Active Arc Fault Suppression System - Internal Arc Detection and Suppression Device Based on Optical Signals. The purpose is to regulate...

Define the performance requirements and test methods for internal arc detection and suppression equipment based on optical signals, as well as other product-related requirements.

The thermal protection system referred to in this document is based on the principle of monitoring the temperature of the protected component and is designed to prevent the rotating motor from malfunctioning due to cooling system failure.

Simple and effective measures can be taken to address excessive temperature rise caused by factors such as high ambient temperature, while protection systems that rely solely on monitoring current cannot handle all situations.

Under these circumstances, this type of protection must be ensured.

Since the operating temperature and response time of the thermal protection system are predetermined and cannot be adjusted according to the corresponding motor operating conditions, therefore...

Its protective function cannot fully cover all fault conditions or improper use of the motor.

A thermal protection system conforming to this document may consist of a PTC thermistor with an associated control unit.

And at a certain point in the PTC thermistor's characteristics, it can be converted into a switching function. Thermal protection systems are widely used, and in all cases, the electrical mechanism...

Manufacturers install PTC thermistors in motors; motor manufacturers either provide the control unit with the motor or specify the type of control unit to be used.

Specific requirements for control units.

The control unit is often considered part of the control system and does not necessarily need to be supplied with the motor; therefore, interchangeable systems are possible.

The interchangeable system specifies the correlation characteristics between the PTC thermistor and the control unit. This particular system cannot be considered superior to the one specified in the original text.

This system is compatible with other systems described in this document, but may be used in certain fields and is referred to as "Type A".

Low-voltage switchgear and control equipment Part 8: Installed Thermal Protection for Rotating Electrical Machines (PTC) control unit

1 Scope

This document specifies the requirements for the control unit, which, based on the changes in PTC thermistors in rotating electric machines and industrial applications, performs...

Control of electrical switches.

This document specifies such systems, including positive temperature coefficient (PTC) thermistors with specific characteristics and their associated control units.

Require.

This document includes.

---Characteristics, structure, performance, and testing of the control unit; and

---The association between the "Type A" control unit and the PTC thermistor.

This document does not include.

---For thermal protection of rotating electrical machines and their maximum winding temperature, see GB/T 13002;

---For use in explosive atmospheres [see GB/T 3836 (all parts)];

---Software and firmware requirements;

Note 1.GB/Z 41912-2022 provides guidelines for embedded software.

---Network security (see GB/Z 43030).

Note 2.Since the operating characteristics of the control unit depend on certain aspects of the PTC thermistor, it is impossible to specify all the requirements for the operating characteristics of the control unit.

Some requirements for thermal protection systems can only be considered when taking into account the characteristics of the protected rotating motor and the installation method of the PTC thermistor inside the motor.

Sure.

This document applies to in-cell thermal protection (PTC) control units for rotating electrical machines.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are not included.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

GB/T 2423.5 Environmental testing – Part 2: Test methods – Test Ea and guidelines. Impact (GB/T 2423.5-2019) IEC 60068-2-27:2008, IDT GB/T 2423.10 Environmental testing – Part 2: Test methods – Test Fc. Vibration (sine) (GB/T 2423.10-2019) IEC 60068-2-6:2007, IDT GB/T 2828.1-2012 Sampling Procedures for Inspection by Attributes – Part 1: Lot-by-lot Inspection Sampling Indexed by Acceptable Quality Limit (AQL) Plan (ISO 2859-1:1999, IDT) GB 4824-2025 Limits and methods of measurement for radio frequency interference characteristics of industrial, scientific and medical devices (CISPR11.2024, IDT) GB/T 5465.2 Graphical symbols for electrical equipment - Part 2: Graphical symbols (GB/T 5465.2-2023, IEC 60417 Data-(base 2023-03, IDT) GB/T 14048.1-2023 Low-voltage switchgear and controlgear – Part 1: General (IEC 60947-1:2020, MOD) Note. There are no technical differences between the content referenced in GB/T 14048.1-2023 and the content referenced in IEC 60947-1:2020.