Underground Cable

The underground cables have several advantages over the overhead lines; they have smaller voltage drops, low chances of developing faults and have low maintenance costs. However, they are more expensive to manufacture, and their cost may vary depending on the construction as well as the voltage rating.

Types of underground cables

The underground cables are classified in two ways; by the voltage capacity, or by the construction.

By Voltage

LT cables: Low-tension cables with a maximum capacity of 1000 V

HT Cables: High-tension cables with a maximum of 11KV

ST cables: Super-tension cables with a rating of between 22 KV and 33 KV

EHT cables: Extra high-tension cables with a rating of between 33 KV and 66 KV

Extra super voltage cables: with maximum voltage ratings beyond 132 KV

By Construction

Belted cables: Maximum voltage of 11KVA

Screened cables: Maximum voltage of 66 KVA

Pressure cables: Maximum voltage of more than 66KVA

Low and medium voltage cables

Belted cables

The cores in the belted underground cables are not circular and are insulated by impregnated paper. The cores are generally stranded and may be of non-circular shape to make better use of available space. In a 3 phase cable, the three cores are grouped together and then belted with the paper belt.

The gaps between the conductors and the paper insulation are filled with fibrous material such as the jute. This makes the cable to have a circular cross-sectional shape. A lead sheath is used to cover the belt hence protect it from moisture and provide mechanical strength. The lead sheath is then covered with a single or multiple layers of an armoring material and finally an outer cover.

Disadvantages:

Since the electrical field in the three core cables is tangential, the paper insulation and the fibrous materials are subjected to the tangential electrical stresses. This stresses weakens the fibrous material as well as the resistance and dielectric strength for the insulation along the tangential path.

The weakening of the insulation may lead to the formation of air spaces in the insulation. Under high voltages the air may be ionized and cause deterioration and breakdown of insulation. For this reason, the belted cables are only suitable for voltages up to 11KVa and not higher.

Due to the large diameter of the paper belt, bending the cable may lead to the formation of wrinkles and gaps.

DAYA Underground Cable Details

DAYA Underground Cable Working conditions

Pressures cables

These are high power cables used for voltages above 66KV. The cable construction is different from the above two and majority uses a cooling gas or oil.

Benefits of using underground cables:

Suitable for congested urban areas where overhead lines may be difficult or impossible to install

Low maintenance

Small voltage drops

Fewer faults

Not susceptible to shaking and shorting due to vibrations, wind, accidents, etc.

Not easy to steal, make illegal connections or sabotage

Poses no danger to wildlife or low flying aircraft.

Disadvantages of underground cables

More expensive

Difficult in identifying and repairing broken cables

Damage to cables or electrocution may occur to people digging the ground and if they are unaware of the cable’s existence

Specifications:

Size (AWG or KCM): 636.0

Stranding (AL/STL): 26/7

Diameter Inches: Aluminum: 0.1564

Diameter Inches: Steel: 0.1216

Diameter Inches: Steel Core: 0.3648

Diameter Inches: Cable OD: 0.990

Weight lb/1000FT: Aluminum: 499.

Weight lb/1000FT: Steel: 276.2

Weight lb/1000FT: Total: 874.1

Content %: Aluminum: 68.53

Content %: Steel: 31.47

Rate Breaking Strength (lbs.): 25,200

OHMS/1000ft: DC at 20ºC: 0.0267

OHMS/1000ft: AC at 75ºC: 0.033

Ampacity: 789 Amps

Packing:

--100m/Coil with Shrinking Film Wrap, 6 Coils per outer carton.

--100m/Spool, spool can be Paper, Plastic, or ABS, then 3-4 spools per carton,

--200m or 250m per Drum, two drums per carton,

--305m/Wooden Drum, one drum per outer carton or pallet loading,

--500m/Wooden Drum, one drum per outer carton or pallet loading,

--1000m or 3000m wooden drum, then pallet loading.

*We can also offer customized OEM packing according to clients' request.

Delivery:

Port: Tianjin, or other ports as per your requirements.

Sea freight: FOB/C&F/CIF quotation are all available.

*For some countries such as Africa countries, middle east countries, our sea freight quotation is much cheaper than clients get from local shipping agency.

DAYA Underground Cable Parameter (Specification)

DAYA Underground Cable Service

Pre-sales

We provide technical support and complete power distribution solutions tailored to your needs. If the design drawings you provide are deemed unfeasible, we will optimize the plan and adjust it with the dimensions of the cabinet, the location of the equipment, and so on. We will also optimize the configuration of the products to make them meet your requirements.

After-Sales

If any problem occurs, we will first provide support by phone or email. We will perform a remote debug if necessary. Furthermore, our products come with a troubleshooting manual for reference when trying to find the fault and solve issues by yourself. Most problems can be solved by the above-mentioned methods. We will check in every year or so to acquire detailed information about your equipment to get a better understanding of the inner workings.

Our customer service promise

1. We will quickly solve the problem after receiving the issue report or repair request.

2. We then explain the cause of failure in detail and any fees will be charged according to market pricing.

3. If we take any parts back for inspecting, we will apply fragile notice stickers on them or write their serial number down to maintain the safety of the parts.

4. If your complaint is deemed valid, we will refund repair fees to you on-site.

DAYA Underground Cable FAQ

1.Q: Are you a manufacturer or trader?

A:We are all, Main business of the company low-voltage switchgear, power distribution cabinet, explosion-proof cabinet design, production and system programming.

2.Q: Whether to support OEM/ODM?Can you design the equipment according to our size?

A: Of course, we can customize any product according to customer requirements, and we can provide design solutions and solutions.

3.Q: Why should I buy from you instead of someone else?

A: First of all, we can provide all customers with very professional support consisting of IT consultants and service teams.Secondly, our main engineers have more than 20 years of experience in power distribution equipment development.

4.Q:What about the delivery time?

A:Generally, our delivery time is around 7-15 days about. While, it depends on the requirement of customers and the

quantity of products.

5.Q:What about the shipment?

A:We can arrange shipment by DHL, FedEx, UPS,etc.of course, customers can also use their own freight forwarders.

6.Q:How about the terms of payment?

A:Supported T/T、Paypal、Apple Pay、Google Pay、Western Union,etc. Of course we can discuss on this.