Quality Points for Connecting Cables of Diesel Generator Sets

The quality requirements for connecting cables of diesel generator sets are extremely critical because they directly affect the safety, reliability, stability, and service life of the entire power supply system. Using "illegal" cables may cause excessive voltage drop, cable heating, and even serious damage such as fire. Therefore, the connecting cables for diesel generator sets shall comply with the requirements of relevant international standards. If there are conflicts with the local power supply bureau's requirements regarding brand, model, color, etc., compliance with the local power supply bureau's requirements shall prevail. For types such as ZA-YJV, ZA-YJV22, NH-YJV, WDZA-YJV, NH-KVV, WDZA-BYJ, WDZA-YJY, which are not specified types for diesel generator connecting cables under YD/T1173, implementation shall be according to relevant standards such as GB/T12706, GB/T19666, JB-T10491, GB/T9330, and GB/T5023.

(1) Cross-sectional Area: This is one of the more important parameters. The cross-sectional area must be accurately calculated based on the generator set's rated output current, cable length, and permissible voltage drop.

(2) Simple Principle: When meeting voltage drop requirements, it is better to be larger rather than smaller. The current density is generally recommended to be between 2-4A/mm², depending on the installation method and ambient operating temperature. 

(3) Voltage Rating: The voltage rating of the insulation layer must be higher than the rated voltage of the generator set. For example, for a 400V system, cables with a 0.6/1kV rating are typically used.

(4) Voltage Drop:
This is a key indicator for measuring the efficiency of electrical energy transmission. Excessive voltage drop can cause insufficient voltage at the load end, endangering the normal operation of equipment, while electrical energy is dissipated as heat in the cable. Generally, the total voltage drop is required not to exceed 3%-5% of the rated voltage. In practical engineering, to leave a margin, more detailed divisions are usually made for the installation:

(1) Generator Main Connecting Cable (Generator → Main Switchboard / ATS): It is recommended to control the voltage drop to ≤2%. The reason is that as the main artery of the power supply, space must be left for the voltage drop of subsequent distribution circuits to ensure the total voltage drop of the entire installation is within the acceptable range.

(2) Entire Power Supply System (From Generator Terminals to the Farthest Load Device): The total voltage drop should not exceed 5%. This includes the sum of all voltage drops from the generator main cable, distribution cables at all levels, and the final branch circuits.

(5) Conductor:

(1) Conductor material should be TR type soft round copper wire or TXR type tinned soft round copper wire.

(2) The DC resistance of single wires at 20°C shall comply with the provisions of the table below.

(3) Reference data table (Placeholder).

(6) Insulation

(1) Cables should be marked with clear identification.

(2) The insulation resistance value should meet relevant standards. 

(3) Insulation performance should be stable and reliable.

(4) The average thickness of the connecting cable insulation layer: shall not be less than the nominal thickness , and the minimum thickness at any point shall not be less than 90% of the nominal thickness minus 0.1mm.

(5) Core Identification: Each insulated core should be identified by color. The identification method shall comply with local  requirements. The successful bidder will receive color requirements from Cummins users.

(6) Intermediate Inspection: The insulated cores of the diesel generator connecting cables shall withstand the power frequency or DC spark test specified in relevant standards as an intermediate inspection. 

(7) Sheath:

(1) Sheath Material: It should have excellent flexibility, oil resistance, wear resistance, weather resistance (UV, ozone), tear resistance, and flame retardancy

(2) Sheath Requirements: The sheath shall be smooth, uniform in thickness, free from defects such as pinholes and bubbles. It should ideally possess excellent flexibility Cummins diesel generator oil resistance, wear resistance, weather resistance (UV, ozone), tear resistance, and flame retardancy, making it very practical for moving, dragging, and outdoor complex environments.

(3) Sheath Thickness: The nominal thickness of the cable sheath shall comply with the provisions . For non-armoured cables, the minimum sheath thickness at any point shall not be less than 85% of the nominal thickness minus 0.1mm; for armoured cables, the minimum sheath thickness at any point shall not be less than 80% of the nominal thickness minus 0.2mm.

(4) Composition inside Sheath: For cables where the sheath is in direct contact with the insulation or inner covering, the cable sheath shall not adhere to the insulation or inner covering. Talc powder or other materials meeting the cable performance requirements can be used as a separator between the insulation or inner covering and the sheath.

(5) Sheath Color: Usually black, as carbon black provides excellent UV resistance. 

(6) Shielding Layer (for large capacity or long-distance transmission): If the environment has strong electromagnetic interference, or to reduce the cable's own electromagnetic radiation to the outside, consider using cables with copper wire braid or copper tape shielding.

(8) Other Technical Requirements:

(1) Type Designation: The type designation for diesel generator connecting cables consists of six parts: combustion characteristic code, series code, insulation material code, sheath material code, outer covering code, and operating temperature code. Its structure shall comply with the requirements of relevant specifications.

(2) Cable Type: The number of conductors, nominal cross-sectional area, and rated voltage of the diesel generator connecting cable shall comply with the requirements of relevant specifications.

(3) Minimum Bending Radius during Installation: Shall not be less than 8 times the outer diameter of the diesel generator connecting cable for non-armoured types, and not less than 15 times the outer diameter for armoured types.

(4) Oil Resistance: There may be oil stains around the generator set. The cable sheath must have good resistance to mineral oil to prevent the sheath from swelling, deforming, or aging.

(9) Selection Recommendations:
To ensure the quality of cables connecting diesel generator sets, heavy-duty rubber sheathed flexible cables (such as national standard types YCW, YHZ) should be the first choice. These are ideally designed for power supply to mobile electrical devices. If the cables are permanently fixed and installed in cable trays or conduits in a good environment, VV or YJV type power cables can also be considered, but their flexibility is far inferior to rubber sheathed cables. In summary, the core principle for selecting connecting cables for diesel generator sets is to use "flexible cables with a sufficiently large cross-sectional area, pure copper conductors, and a heavy-duty rubber sheath", and ensure they comply with safety standards. Never cut costs on this item to avoid losing more due to less.

Repair and Technical Support: Cummins, as a globally renowned brand, incorporates comprehensive analysis steps combining mechanical, electronic, and intelligent mechanisms in its diesel generator set troubleshooting technology, enabling quick problem identification and reduced downtime.