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Instruction to Install Cables and Connect Wire of Diesel Genset

Nov. 01, 2018

Precautions for the installation of diesel generator set cable

There are some places to pay attention to the installation of diesel generator set cable. Let's take a look:


I Line tube


1. The line pipe should be selected according to local regulations.

2. The surface laid pipe should be supported and fixed, and the pipe must be grounded.

3. The pipeline system should be laid before the cable is introduced. At least 40% of the space should be in the conduit. The radius of the bend of the elbow should not be less than 2.5 times the outer diameter of the conduit.

4. The brigade system should be able to prevent the ingress of dust and water. Vents shall be designed at the highest and lowest points of the pipeline, and the open-disposed piping shall be composed of good fireproof materials.

Instruction to Install Cables and Connect Wire of Diesel Genset.jpg


II Trunking


1. Steel trunking should follow the relevant regulations.

2. Make sure that there is sufficient bending radius when installing. As with steel conduits, the use of steel trunking as a protective material for conductors is in accordance with the relevant wiring rules, but cannot be used for combustion protection.

3. At least 45% of the space in the trunking, the trunking should have the correct support and fixing points.

4. The trunking cover should not be placed on the underside of the wire trough. When passing through walls, floors and ceilings, the trough cover should be tight. The vertically arranged wire trough should have a suitable heat-resistant material inside to prevent the temperature in the top region from being too high.


III Line isolation


Separation measures should be taken for different line cables to prevent electrical and physical contact. There are three types of lines defined in the specification:


1. Low voltage line powered by mains (except for fire or emergency lighting).

2. Ultra-low voltage or communication lines (such as telephone, address and data transmission systems) powered by a safe power source.

3. Fire alarm or emergency lighting.


IV Cable tray


1. The most common method is to lay the cable on the perforated cable reel. The cables are arranged flat and the maximum fastening distance is 450 mm.

2. The support spacing of the support of the cable drum is typically 1200 mm. The cable reel should have sufficient strength and should be selected to have an additional cable capacity close to 25% of the load carrying cable.


V Cable trench


1. Cable trenches in generator rooms and equipment rooms should be enclosed (with concrete or tiled iron panels).

2. Cable trenches should be constructed with the smallest possible bend radius for the largest cable.

3. The cable trench is as straight as possible, and its surface is smooth and has a slope so that water and oil can be drained to the sump.


VI Underground laying


1. Armored shielded cables can be laid directly underground and should have a 75 mm thick implant. The distance between the high and low voltage cables in the cable trench or only underground is between 160 mm and 400 mm.

2. When passing through a road, passage or building structure, the cable should be protected from mechanical damage by conduit or guards. Reserve a certain amount of space for future cable laying.


What are the precautions for the connection of diesel generator set wires?


The power line connection of the diesel generator set output to the load should be carried out by a qualified and experienced electrician, as well as repair and maintenance. In addition, the wiring of the unit must comply with the relevant electrical or other requirements, including grounding and ground fault protection requirements. The following is a detailed introduction to the connection precautions for the diesel generator set wires.




Due to the vibration of the generator, the connecting generator should use a flexible wire so that when the generator is displaced, the connection column of the alternator or the power air switch is not damaged. If the flexible wire cannot be used due to installation problems, the generator can be used nearby. A junction box is installed, and a section from the box to the machine is connected by a flexible cord. The wiring should be placed on the pipeline or the trunking and must not be fixed on the generator set. If the wires need to be bent, please refer to the minimum bending radius.


The wires must match the voltage and current output from the generator. Before determining the thickness of the wire, it is necessary to consider the indoor temperature, the installation method and other wires side by side. When using single-core copper wire, the sealing sheath should be made of non-magnetic metal such as aluminum or copper, or non-metal. If a magnetic metal sheath is used, JC's method is to cut the gap in the sheath to ensure that the current does not generate eddy currents.


All interfaces must be checked for firmness. Whether the phase is the same as the mains, this is especially important when using the automatic switch or when the unit is used as a parallel.




The connection generator and load are protected by a disconnect switch that automatically disconnects the circuit during overload or short circuit.




When designing the power supply system, ensure that the load is balanced. Do not load the one phase far more than the other, which will cause the coil of the alternator to overheat. 


Phase and phase imbalances can also damage sensitive three-phase equipment connected to the consumer system. Make sure that the current of one phase is not exceeded by the current of the generator. If it is necessary to connect the unit to the existing power supply branch, it must be considered for redistribution in order to balance these loads.


Power Factor


The power factor (COS) of the load must be calculated on the design. If the power factor is below 0.8 hysteresis (inductance), the generator will be overloaded. The most smooth operating power factor of the output of this unit is 0.8-1.


Pay particular attention to the presence of advanced power factor when installing automatic or manual power factor correction devices such as capacitors. This will result in voltage instability and destructive ultra-high voltages. In general, all power factor correctors are turned off when the generator is supplying power.


Grounding requirements


1. The grounding requirements are determined by different regions. The base of the machine must be absolutely grounded. Because the generator is equipped with a shock absorber, the grounding wire should be retractable to prevent disconnection due to vibration.

2. The grounded wire or clamp can pass the generator full load current and meet local specifications.

3. Alternator reconnection


Most alternators can be rewired to accommodate different output voltages. Refer to the (Alternator Manual) for any additional voltages, such as power-off switches, current exchangers, and wires, before changing the voltage. Ammeters and more.


Parallel operation


Special equipment is required when standard generators are combined or connected to the grid.


Insulation Test


After installing the generator, do not rush to start, first check the resistance of the coil. The automatic regulator should be disconnected, the rotating diode can be temporarily shorted by wires, or disconnected first, and all controlled lines must be disconnected.


Use a 500V megger or similar instrument to disassemble the wire between the midpoint and ground. Measure the impedance from the terminal to ground. The insulation resistance of the machine to ground should exceed 5MΩ, and the coil must be processed.


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