IEEE C37.20.2a-2020 pdf free download.IEEE Standard for Metal-Clad Switchgear–Amendment 1: Control and Secondary Circuits and Devices, and All Wiring.
Control, secondary, and logic-level wiring used in the equipment and covered by the IEEE 37.20 series of documents share the same requirements for wire type, wire size, protection, and support. Through the years and numerous revisions. the words found in the construction clause of IEEE Std C37.20. I TM EEE Std 37.20 2TM, IEEE Std C37. 20.3TM, IEEE Std C37. 20.TM, and IEEE Std C37.2ITM have changed This amendment serves to standardize the wording and requirements for control, secondary, and logic-level wiring throughout the IEEE C3720 series by providing the changes necessary to update IEEE Std C37.20.2-2015.
Overcurrent protection of current transformer secondary circuits shall not be provided. Open circuit protection should be considered where current transformer wiring connects to devices external to the switchgear assembly.
Primary and secondary protective devices may be omitted from voltage-dividing devices such as capacitive and resistive voltage dividers.
7. 3. 3 Control, secondary, and logic-level wiring
Flame-retardant, 600 V insulated stranded copper wire shall be used for internal wiring between components of switchgear assemblies, and to terminals for connection to external controls, metering, or instrumentation. Wiring within components is assumed to be covered by standards applicable to those devices and is not covered by this standard. Wiring for the purpose of conveying power to external switchgear loads is not covered by this clause.
The switchgear manufacturer is responsible for the performance of the wiring system provided by the manufacturer within the switchgear. This applies to the integrity of internally generated signals in the control wiring, and may require the use of special precautions such as shielded wire, twisted-pair wire, or segregation of certain wires.
Wiring for current transformer and shunt trip circuits shall be no less than No 14 AWG, regardless of load.
Thermocouple wiring is specifically excluded from the above ampacity requirements. It shall meet the voltage, current, and temperature requirements of the circuit in which it is used and the location where it is installed.
When required for connection to a specific component, low-energy signaling, and communication wiring is specifically excluded from the above ampacity requirements. The wire shall meet the voltage,current, and temperature requirements of the circuit in which it is used and the location where it is installed.
NOTE:Where long connections to the control source are necessary, the cable must be large enough to prevent excessive voltage drop.
IEEE C37.20.2a-2020 pdf download
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