Marine VFD Cable

  VFD stands for variable frequency drives. Marine VFD is a special type of marine cable which is popular for its outstanding electromagnetic compatibility. 

Marine VFD cables can transfer power from AC drive systems to AC motors. These cables also have the ability to maintain great performance even in harsh conditions.

  It can achieve extreme conditions of temperature, humidity, salt corrosion, oil and vibration. 

Some special marine VFD cables have been designed specially for protecting the safety and health of crew working on the ship boards.

The cables have developed properties. They are flame retardant, halogen free, fire resistant and they produce less smoke.

These cables are electrically balanced and shielded for keeping them safe and functional in water. They have special cross-linked polyethylene insulation.

Figure 1 – Marine VFD Cable

 The basic function of a VFD and a normal wire are almost similar. However, there are some differences among the two. Some of the differences are as follows

• A normal wire consumes more units of electricity as compared to the VFD cables.
• VFD cable can save electrical costs whereas a normal wire brings much more electric bill.
• A normal motor cable has only one ground conductor whereas a VFD cable has three ground conductors with three phase wires.
• The purpose of a normal wire is to enable the continuous flow of power. It carries the circuit back to its original power source.

 It circulates current through electrical systems. On the other hand, the basic purpose of a VFD cable is to organize and protect the drive input power and motor power wiring.    

A shipboard VFD is designed for special commercial purposes. Marine VFD cables are made from tinned copper conductors with special insulators.

It has three phase wires which are phase shifted by 1200 from each other. The cable can bear harsh conditions of temperature, humidity and oil.

They can be used at 900C. the VFD cables are resistant to sunlight, moisture and abrasion.

The shield is made from aluminum or mylar type. The shield is made from 90% TC braid, outer jacket is PVC and the insulation is XLPE.

It has 3 tinned copper conductors and 3XLPE insulated TC grounds. The marine VFDs operate mostly at 480 volts and the cable rating is 600 volts.

 A diode rectifier can be used along with a closed loop voltage to control voltage in the marine VFDs.

An energy report shows that almost 60 percent of the power produced on a boat is used to function the motor pumps.

The traditional control valve, hydraulic and turbine methods are used to control the pumps. The pumping systems can get improved energy efficiency.

The VFD is a device which works to change the speed of a 3-phase induction motor. It changes the frequency of power supply to the motor. The speed of motor is directly proportional to the supplied frequency.

VFD offers great control on flow, speed and pressure. This helps in saving a lot of energy. Variable frequency drives can help in saving energy in every application they are used.

This can be explained by the example of a motor. If we run a motor at reduced speed, it will run on less torque. Lesser torque consumes less current and hence energy is saved.

Figure 4 – Construction of Marine VFD Cable

EMC stands for electromagnetic compatibility. As the name of the cable indicates, the EMC cables have excellent electromagnetic capacity.

EMC cable is very useful for fixed installations. It is applicable in most areas and open deck in ships.

The EMC cables have very high-density shield and compound shield. These shields enable the EMC cable to offer great anti-electromagnetic interference.

 Mostly, the EMC cables are fire resistant and flame retardant. Both the types of EMC cable are produced by a special low flame thermosetting compound which is halogen free.

 They feature low smoke, halogen free and flame retardant. The cable has stranded tinned copper wire with XLPE insulation.

The outer sheath is made from thermoplastic compound and the inner core is a strong white colored wire.

 The yacht batteries must be charged regularly to keep the system working. The charger discharges itself once it is fully charged even when it is left to sit.

Figure 5 – A Marine EMC Cable

Before you make a connection of the shore power with your boat or other device, make sure that all the systems are completely shut off.

The power pedestal and the AC switches on the electric panel onboard should not be turned on.

For the connection of a marine shore power, you will need a marine cord set. A marine cord set is a shore power cord, mostly yellow and 25 feet long.

 This cord set has a male connector on one side which plugs into the female receptacle present on the power pedestal on the dock.

 The female connector on the other side connects to the male outlet which is located somewhere on the vessel.

Once you are done with this arrangement, push the male connector into the pedestal. Then slightly twist the connector clockwise to secure.

 All this connection does not require any adapters.

The battery of the yacht is chargeable through a battery charger and shore power.

The vessels that spend most of their time on the dock require smaller chargers because they are constantly hooked up to shore power.

Figure 6 – A Shore Power Connection

The shore power cable has many benefits over a normal wire. It is reliable, long-lasting and easy to install. Besides these basic advantages, there are many other useful aspects of using the shore power cables. Some of them are described as follows

• Reduced operating hours

The most expensive part of a ship is its engine. The engine needs to be maintained properly. It is a great expense to keep a diesel engine ready to use at any time.

The life of an engine is reduced with every hour of its usage. A continuously running engine costs a huge amount of money in fuel as well as maintenance.

The owners of yacht can reduce these expenses by using the marine shore power system. The shore power system can run all the amenities and equipment onboard the yacht.

• Easy installation

The shore power systems are installed horizontally or vertically. This installation provides flexibility for finding a suitable location for its installation.

It can be installed in small spaces as well. The system is light-weighted and its compact design adds an aesthetic finish to the yacht finish. It also adds to the resale value of the yacht.

• Reliable

The shore power system is specifically designed from the ground up for marine use. The output of the system remains regulated no matter what the outer conditions.

The shore power system can work constantly and efficiently in high temperature marine environment. It can work with any marine power system internationally.

• Durable

The shore power systems are very long-lasting. They work on any journey. You can be totally dependent on the shore power while travelling through sea.

The shore power cleans and conditions the electricity. It improves the life span of the marine electronic equipment onboard the yacht.

Figure 7 – A Marine Shore Power Cable

A shore power has a very simple use in general and also on the boat. It works by plugging the boat into a power source.

The power source of a boat is usually present on the dock. The power source transfers alternate current to the boat.

An electrical tower which is also known as power pedestal is present on the dock of the boat. The power pedestal has an AC plug within it which can connect to the shore power.

This connection of the shore power and the AC plug on the yacht offers electric onboard to add to your enjoyment.  

A marine VFD cable comprises of an AC motor, a controller and an operator interface. The variable frequency of the voltage is useful for providing a change in the speed of AC induction motor.

 According to the principle, the electronic controller is designed to alter the frequency of the voltage of induction motor.

Figure 8- working of the marine VFD cable

The advanced VFDs can work as an extremely versatile device. It will control the speed of the motor and protects the excessive current flow during ramp-up and ramp-down conditions.

The VFD cable has a very big advantage that it does not let the motor pull extra current at the start so the utility bills are kept very low.

The VFDs have the ability to control the speed of motor and the direction of turning of motor shaft. So, the torque which the motor provides can be sensed. 

There are many types of VFDs depending upon the way it converts AC into DC power and rectification. However, there are three main types of VFDs. VSI, CSI AND PWM.

• VSI type VFDs

This is the most common type of VFD. VSI basically stands for voltage-source inverter.

A simple diode bridge converts the AC signal of the output into DC signal output in this type of VFD.

A capacitor is used to store energy. There is an inverter circuit which uses the stored energy to give the output. Its speed range is quite good and the design is simple.

It is very cost effective. These VFDs have a special design that provides smooth output voltage from the variable frequency range.

• CSI Type VFDs

In CSI type of VFDs, the construction of the cable depends more upon current than the voltage because CSI stands for current source inverter.

 In the CSI VFDs, the variable frequency drive uses SCR bridge converter. The series of inductors is used to filter the output energy.

It gives smooth current output. CSI VFDs are a kind of constant current generator.

• PVM type VFDs

PWM stands for pulse width modulation. This type of VFD can be rendered as the improved version of VSI type of VFDs.

The PWM technique makes the VFDs able to provide stable voltage output along with a maintained frequency ratio. A diode bridge rectifies the AC signal into a DC signal.

The duty cycle in a variable frequency range is maintained and controlled with the help of switching circuits.

There is an additional regulator for regulating the output so it provides stable and proper voltage as well as current to the load.

Figure 9- types of marine cables

YUANYANG marine flex cable is produced according to IEC 60092 standard. We manufacture many types of marine cables with high-quality material.

We are dedicated to the development, research and manufacturing of marine, offshore and naval cables. All the types are approved by ABS, BV, CCS, LR, RINA.

Following are some types of marine cables that we manufacture

• Marine flex cable

       This cable is widely used on commercial vessels and shore power connection

• Armored marine cable

       It is used for power, lightening and control on ship boards.

• Marine telephone cable

       It is used for telecommunication and instrumentation on the ship.

• JIS Shipboard Cable

       It is used on commercial vessels and marine application.

• NEK606 Offshore Cable

       It is used for fixed installation on offshore platform and oil rigs.

• Fire resistant cable

       It is designed for fire alarms and special occasions on ship boards.

Variable frequency drives have their applications in many fields. They are used in a number of AC motors to control their speeds.

Some main applications are in conveyor systems, blower speeds, pump speeds, machine tool speeds and many more.

It is helpful in applications where variable speed is required along with the variable torque.

Certain applications like speed control for a conveyor, a remote potentiometer offers the variable frequency service. the personnel can adjust the speed of the conveyor manually.

The personnel which can give minimum and maximum frequencies to the device, is based on the principle of variable frequency drive.

It can be used to control duplex pumps hence reducing the maintenance cost. It can also be used in the swimming pool filtration system or booster pumps.

Variable frequency drives are also useful in the pharmaceutical industries.

The shore power cable has quite a unique name. Shore power basically refers to the source of the power being supplied through the cable.

The main source of power is the shoreside electrical power. Shore powers are actually useful because they lessen the need of the fuel.

This fuel would be used to run the yachts and power them. With the help of shore power, the unnecessary use of fuel is alleviated. It prevents power while in port.

A shore power cable has many accessories. Following are some of the basic accessories of the shore power cable.

1. Zip sleeve cord cover
2. Threaded sealing ring
3. Shore power cord cable clips
4. Shore power cord clips
5. Threaded locking sealing ring
6. Shore power cord storage bag
7. Receptable waterproof cover
8. Shore power cord organizer
9. Shore power cable ring
10. Shore power plugs and connectors

The shore power system is the most reliable and versatile system models in the market today. It has a unique design that makes its installation easier in every situation and any space available.

The installation does not affect the surrounding environment and keeps it clean.

Shore power system reduces the local pollution to a very great extent while being docked. In this way, it is a safer and healthier option.

The shore power is usually 120 volts. The need for extra energy for bigger vessels has brought revolution in the power.

The differences in the frequency along with the voltage keep the current stable.

If this balance is disturbed, the difference makes the machine incompatible.

 The yachts usually have DC electrical system which allows the engine to start and use the lights.

The shore system provides with the AC power supply to the boat from the power pedestal through the help of shore power cords.

The cables used in the variable frequency drives must coordinate with the operating environment and other parts of the system.

 That’s why one should get the right VFD cable to ensure the reliability and lifecycle of the drive.

• Voltage and ampacity

Before you decide to buy the VFD cable, it is necessary to know about the voltage and ampacity of both the motor and the cable.

A cable should have enough voltage to support a motor’s working. The rating of a cable should be higher than that of the VFD.

 Voltage rate is a key character to specify the VFD cables because VFD cables are available in low and medium voltages.

• Application specific

A high performance VFD cable is best for the high frequency designs because they contain high-flex type and high strand counts.

  It is very important to see that you do not use stationary cables for torsion applications and continuous flex.

 The physical characteristics of a cable mainly depend upon its environment of application. They are deeply affected by the environmental impacts like abrasion, sunlight, temperature and chemicals.

• Size of conductor

If you know the load size, then it can be very critical in grabbing the right sized conductor.

Any undersized conductor can damage the insulation material due to increased conductor heating leading to the premature cable failure.

Similarly, an over-sized conductor adds to the cost of the cable and increases the cable OD.

• Construction of the cable

Obviously, the construction of the wire is the most important feature that needs to be noticed before buying a VFD cable.

The insulation and jacketing of the cable are very necessary. The construction of the cable is also linked with the environment and application.

If there are oils or chemicals in the environment then the cable with proper jacketing can withstand.

You should pay special attention to the insulation of the cable.

The cables that have heavy wall of thermoset insulation offer better performance, thermal stability and electrical benefits.

Figure 10 – VFD Cable Selection

Yes, marine cables need to be shielded properly. The proper shielding is necessary to reduce the EMI/RFI noise.

Shielding around the marine VFD cable also provides low-impedance signal return path. It is also useful for preventing the common mode and stray voltage.

Without shielding, the cable or equipment fails in its premature stage.

Figure 11- A Shielded VFD Cable

Small VFD controllers are receptive of charging currents.

 It is important to select the best shielded cables. Mostly the shielding is done with NFPA 79 compilant crosslinked polyethylene insulation.

 The VFD cable shielding is very critical to protect the circuits. The shielding is constructed from a foil and tinned copper.

The shield reflects energy and grounds the electrical noise. Shielding prevents all the hazards in a busy working place.

Figure 12 – A VFD Cable with insulation