This standard applies to:
——A.c. transmission, distribution and utilization systems and equipment for use in such systems with standard frequency 50 Hz having a nominal voltage above 100 V;
——Equipment with standard frequency 50 Hz (but not limited to) having a rated voltage below 120 V;
——Equipment having a d.c. voltage below 750 V;
——A.C and D.C. traction systems;
——D.C. high-voltage transmission system;
——Generator having a.c. and D.C. voltages no less than 100 V.
This standard shall not apply to voltages representing or transmitting signals or measured values.
This standard shall not apply to standard voltages of components and parts used within electrical devices or items of equipment.
Note: A.c. voltage in this standard is the root mean square value and D.C. voltage is ripple-free D.C. voltage value.
2 Normative References
The following standards contain provisions which, through reference in this text, constitute provisions of this standard. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, all parties coming to an agreement according to this standard are encouraged to study whether the latest edition of these documents is applicable. For undated references, the latest edition of the normative document is applicable to this standard.
GB 311.1 "Insulation Coordination for High-voltage Transmit and Transform Equipment" (neq IEC 60071-1:1993)
GB/T 311.2-2002 "Insulation Co-ordination-Part 2: Application Guide for Insulation Co-ordination for High Voltage Transmission and Distribution Equipment" (eqv IEC 60071-2:1996)
GB 1402 "A.C. Voltage of Electric Traction for the Railway Main Lines" (GB 1402-1998, eqv IEC 60850:1988)
GB/T 2900.50-1998 "Electrotechnical Terminology-Generation, Transmission and Distribution of Electricity-General" (neq IEC 60050(601):1985)
GB 4706.1 "Household and Similar Electrical Appliances-Safety-Part 1: General Requirements" (GB 4706.1-2005, IEC 60335-1:2001, IDT)
GB/T 12325 "Power Quality-Admissible Deviation of Supply Voltage"
3 Terms and Definitions
The following term and definition are applicable to this standard.
3.1
Nominal system voltage
The given value used for marking or identifying system voltage.
[GB/T 2900.50-1998, Definition 2.1.21]
3.2
Highest and lowest voltages of a system (excluding transient or abnormal conditions)
3.2.1
Highest voltage of a system
The highest value of voltage which occurs under normal operating conditions at any time and at any point on the system.
It excludes transient voltages, such as those due to system switching, and temporary voltage variations.
3.2.2
Lowest voltage of a system
The lowest value of voltage which occurs under normal operating conditions at any time and at any point on the system.
It excludes transient voltages, such as those due to system switching, and temporary voltage variations.
3.3
Supply terminals
The point where the distribution system of the electricity supply authority and the electrical system of the consumer are connected.
3.4
Supply voltage
The line voltage or phase voltage at supply terminals.
3.5
Supply voltage range
The voltage range at the supply terminals.
3.6
Utilization voltage
The line voltage or phase voltage at receiving end of equipment.
3.7
Utilization voltage range
The voltage range at receiving end of equipment.
3.8
Rated voltage (of equipment)
The voltage assigned generally by a manufacturer, for a specified rated operating condition of a component, device or equipment.
3.9
Highest voltage for equipment
Highest voltage for which the equipment is specified regarding:
a) The insulation;
b) Other characteristics which may be referred to this highest voltage equipment recommendations.
The highest voltage for equipment is the maximum value of the "highest system voltage" (see 3.2.1) for which the equipment may be used.
Note 1: The highest voltage for equipment is indicated for nominal system voltages higher than 1000 V only. It is understood that, particularly for certain nominal system voltages, normal operation of equipment cannot be ensured up to this highest voltage for equipment, having regard to voltage-sensitive characteristics such as losses of capacitors, magnetizing current of transformers, etc.
In such cases, the relevant recommendations must specify the limit to which the normal operation of this equipment can be ensured.
Note 2: It is understood that the equipment to be used in systems having nominal voltage not exceeding 1000 V should be specified with reference to the nominal system voltage only, both for operation and for insulation.
Note 3: Attention is drawn to the fact that in some equipment standards (for example, GB 4706.1 "Household and Similar Electrical Appliances-Safety-Part 1: General Requirements" and GB 311.1 "Insulation Coordination for High-voltage Transmit and Transform Equipment") the term "voltage range" has a different meaning.
