1 General Provisions
1.0.1 This code is applicable to the power supply design of measuring and control instrument of chemical plant and not applicable to the power supply design of instrument repair workshop.
1.0.2 The relevant standards are as follows:
HG/T 20664 Specification of Power Supply Design Engineering for Chemical Enterprises
HG/T 20636.4 Split of Design Work between Instrumentation and Electricity
GB 50058 Electrical Installations Design Code for Explosive Atmospheres and Fire Hazard
GB 50174 Designing Code for Electronic Computer Room
During the implementation of this code, the provisions of current relevant standards of the Nation shall be satisfied too.
2 Instrument Power Supply Scope, Load Level and Power Supply Type
2.1 Power Supply Scope
2.1.1 Power supply for instrument and automation devices includes the following items:
1 Routine instrument system
2 DCS, PLC and supervisory control computer system, etc.;
3 Automatic analyser;
4 Safety Interlock System (SIS);
5 Industry television system.
2.1.2 Power supply for auxiliary facilities includes the following items:
1 Illumination in instrument panel (cabinet);
2 Electric tracing system of instrument and measuring pipeline
2.1.3 Power supply for other automatic monitoring systems.
2.2 Load level
2.2.1 According to the requirements of "Specification of Power Supply Design Engineering for Chemical Enterprises" (HG/T 20664) for classifying the electrical load level, the electrical load of instrument may be classified into two levels, i.e. load with special power supply requirements and Level 3 load.
Note: "Specification of Power Supply Design Engineering for Chemical Enterprises" (HG/T 20664) classifies the electrical load into 4 levels according to the importance of electrical load in continuous production process of chemical industry and the requirements on reliability and continuity of power supply, i.e. Level 1 load, Level 2 load, Level 3 load and load with special power supply requirements.
2.2.2 Under most conditions, instrument electrical load belongs to the load with special power supply requirements. Such kind of load will disturb the production process after power interruption which causes equipment damage, personal injury and economic losses, and so emergency power shall be arranged.
2.2.3 Under minority conditions, instrument electrical load belongs to Level 3 load. Such kind of load will not disturb the production process after power interruption which would not cause equipment damage and economic losses, and it is unnecessary to arrange emergency power.
2.3 Power Supply Type
