what is ct rated cable

Full Answer

What is CT use wire?

There are occasions when longer current transformer (CT) lead wires are needed. If the standard 8 foot (2.4 meter) leads are not long enough, they can be extended to 100 feet (30 m) or more, especially if you keep the wires away from electrically noisy equipment, such as variable speed drives (inverters).

What is TC rated cable?

TC cables are rated for 600 volts and can be used in industrial power or control circuits, where flame retardant cables are desired. Allowed installations include cable trays, raceways, and outdoor locations where supported by a messenger wire.

What are the 3 main types of cable tray?

The cable tray types to choose from are ladder, ventilated trough, or solid bottom.

What does 3c cable mean?

3/C - Three conductor. This is the same as three separate conductors, except that the conductors are encased with an insulated overall outer jacket effectively forming one cable. The cable may or may not have an interstitial ground wire.

What is JP rated?

The “JP” rating means that the cable has been tested to withstand the same pulling stresses through framing members as nonmetallic-sheathed cable.

What is Type MC cable?

(NEC Article 330) – Metal Clad cables are assemblies of one or more insulated circuit conductors with or without optical fiber members enclosed in an armor of interlocking metal tape, or a smooth corrugated sheath. A plastic overall jacket can also be provided.

What are the six 6 main types of cable tray?

Type of Cable Trays:Ladder Type Cable Tray.Solid Bottom Cable Tray.Trough Cable Tray.Channel Cable Tray.Wire Mesh Cable Tray.Single Rail Cable Tray.

How many types of cable are there?

There are more than 20 different types of cables available today, designed for applications ranging from transmission to heavy industrial use. Some of the most commonly-used ones include: Non-Metallic Sheathed Cable : These cables are also known as non-metallic building wire or NM cables.

What type of wire is tray cable?

XHHW tray cable is a robust cable made with a thermoset insulation. It is a cross-linked polyethylene building wire with high heat and water-resistance.

What is 1c cable?

Cable single core means that there is only one conductor in one insulating layer.

What does SJTW mean?

SJTW is an industry-standard abbreviation used on wire and cable. S is for service; J for junior (defined as hard service instead of extra hard); T is the coating (thermoplastic/vinyl); W is weather approved.

What does 600V wire mean?

What is 600 Volt Wire? Among other technical specifications, wires are given a rating according to the voltage to which they can be safely exposed. For example, wire rated to 600 volts indicates that 600 volts of potential is the greatest voltage the wire can be exposed to, given its resistivity and conductivity.

Can Soow cable be used in cable tray?

It is not an "Other factory-assembled, multiconductor....specifically approved for installation in cable trays" unless it is specifically approved by the AHJ. (If you look at the definition of "Approved" the AHJ is the only one who can approve something).

Is tray cable rated for direct burial?

XPTC tray cable is used as power and control cables in dry and wet locations and can be installed in cable trays, raceways, and open air. It is weather and exposure resistant and is suitable for use in direct burial, and for class 1, Division 2 hazardous locations.

What is VFD rated cable?

VFD cable offers the proper shielding needed to reduce EMI/RFI noise and to provide a low-impedance signal return path — preventing the common-mode or stray voltage that leads to premature cable and/or equipment failure. Smaller-sized VFD controllers are even more susceptible to charging currents.

Where can tray cable be used?

Tray cable comes in multiconductor and multipair styles that can be used for control, instrumentation/signal, power and lighting. Tray cable is the all-around cable. It can be used in wet or dry locations, indoors or outside, and shielded or left out in the open.

How many feet are CT wires?

Our standard twisted black and white CT wires are available in 100 foot (30 m) coils, see the CT Wire page for details.

What is CT interference?

CT signals are susceptible to common-mode and differential-mode interference, magnetically and capacitively coupled into the wires. The twisted-pair arrangement blocks most magnetically coupled and differential noise, but does not reject common-mode, capacitively coupled noise. A shield can help block common-mode capacitively coupled noise, but is most effective if both ends are grounded. If only one end is grounded, the ungrounded end will oscillate up and down with the interfering signal, and then couple into the twisted pair wires.

What gauge is twisted wire?

Twisted – Our standard black and white #20 AWG gauge CT leads are twisted. Twisting is important for noise immunity, especially at 50-60 Hz. This wire is available in 100 foot (30 m) coils, see the CT Wire page for details.

What voltage is shielded cable?

Shielded cable is typically available in 300 and 600 volt ratings. The 300 Vac rating is sufficient for 120/208/240 Vac panels and circuits, but 600 V rated cable should be used for 277/480 Vac and 347/600 Vac panels.

How long can a transformer lead wire be?

There are occasions when longer current transformer (CT) lead wires are needed. If the standard 8 foot (2.4 meter) leads are not long enough, they can be extended to 100 feet (30 m) or more, especially if you keep the wires away from electrically noisy equipment, such as variable speed drives (inverters). To minimize power line noise from interfering with sensitive CT signals, extension wires should be run in conduit (raceway) without any power conductors.

Can you extend 8 foot lead wire?

When the 8 foot lead wires on standard stock CTs are not long enough, you can extend them by splicing on additional wire. You may want to shorten the original CT wires, especially if you are going to use shielded cable and ground the shield to earth ground.

Does long cable reduce CT signal?

Long lengths of cable can slightly attenuate the CT signals (in addition to increasing susceptibility to noise). The following table shows the required total CT length to reduce the CT signal by 0.1% as a function of AWG, based on the WattNode CT input resistance of 23 kilo-ohms.

What is the secondary current rating of a CT?

The secondary current rating of a CT is either 1 A or 5 A. CTs with a 5 A secondary rating are becoming less common as more CT driven equipment becomes digital. For long secondary cable runs, CTs with 1 A secondary windings can minimize the transformer and secondary cable size.

What is the protection class rating of a 200/1 A CT?

A 200/1 A CT has a protection class rating of 5P15. The secondary current is guaranteed to be linear up to 15 times the rated primary current. The secondary current will be 1 A (+/-1%) at 200 A primary current and 15 A (+/-5%) at 3000 A primary current.

What class of protection is used for current based protection relays?

Use a 5PX protection class CT for current based protection relay inputs. The ALF must be selected so that the relay trip point lies on the linear part of the secondary current curve, between 50% and 100% of the ALF.

How much current should a CT metering unit have?

Metering CT’s primary current rating should not exceed 1.5 times the maximum operating current. Protection CT’s primary current rating needs to be chosen so that the protection pick-up level is attained during a fault.

What is the maximum allowable secondary burden for a current transformer?

This example indicates a current transformer with an accuracy of ±0.5%, and a maximum allowable secondary burden of 0.1 Ω (or 2.5 VA on a 5 A secondary CT). This is a metering class rated current transformer.

What is a CT transformer?

A current transformer (CT) is designed to produce a secondary current which is accurately proportional to the primary current. It consists of a single primary winding, which an external busbar or cable runs through, or it can have a single primary bar, brought out to two ends for termination.

What is a protection class CT?

A protection class CT provides a linear transformation of the primary to secondary current at high overload levels. This characteristic makes them suitable for use with overcurrent protection relays.

What is cable tray rated?

In general, tray rated cables are quality products that have been tested to withstand the rigors of severe environments. They are protected by either a plastic Jacket or metal armor over individual conductor insulations. They can be rated for outdoor, indoor, for corrosive areas, for hazardous locations, or high electrical noise areas. They should be UL listed indicating they have been tested for ratings relative to flammability resistance, mechanical resistance and temperature limitations. Many cable tray rated cables include a crush and impact test as part of the listing and are rated as exposure rated (ER). ER cable is allowed to leave the cable tray for distances up to six feet, as long as it is supported and secured.

What voltage is TC cable?

TC cables are rated for 600 volts and can be used in industrial power or control circuits, where flame retardant cables are desired. Allowed installations include cable trays, raceways, and outdoor locations where supported by a messenger wire.

Why separate PLTC and ITC cables?

Even if shielded, both PLTC and ITC cables should be separated from 600-volt power cabling to avoid noise or cross talk. This is generally accomplished through a barrier strip within the cable tray. Whenever possible it is considered best practice to route power and instrumentation cables is separate trays.

What article of NEC is the fill capacity for optical fiber cables?

Cable tray fill capacities for optical fiber cables are not addressed in NEC Article 770 nor Article 392. Designers and installers should refer to the cable manufacturer for guidance.

What is a tray cable?

The most frequently used tray cables are: Type TC – Tray Cable – (NEC Article 336) –Power and control tray cable type TC is a factory assembly of two or more insulated conductors, with or without associated bare or covered grounding conductors, under a non-metallic jacket.

How far can ER cable be left in a cable tray?

ER cable is allowed to leave the cable tray for distances up to six feet, as long as it is supported and secured.

What type of cable is used in a cable tray?

Although less commonly used, several other types of cables are permitted to be installed in cable trays. These include: Type AC, CATV, NM, NMC, NMS, SE, USE and UF. As with the cables discussed in this Bulletin users should refer to the associated NEC Article for the proper wiring methods for each type of cable.

When should you use a tray-rated cable?

336.10 (7) from 2014. If a cable must run outside of a tray for any length, a tray cable ra ted for “exposed-run” (ER) must be used.

What makes a tray-rated cable different from a standard multi-conductor?

Tray cables are high-quality cables that have been tested rigorously and generally boast armor over individual conductors for superior insulation and a robust jacket that can withstand heavy abrasion. Tray cables also pass stringent impact and crush tests per UL 1569 and do not require the use of conduit. This lowers installation and maintenance costs, while also making routing during installation quicker and easier, especially when using tray-rated cables with flexible jackets, like ÖLFLEX®190 & ÖLFLEX®190CY, ÖLFLEX® AUTO-I, and more.

What is tray cable?

According to the NEC (National Electric Code), tray cable is defined as “a factory assembly of two or more insulated conductors, with or without associated bare or covered grounding conductors under a nonmetallic sheath, for installation in cable trays, in raceways, or where supported by a messenger wire.” Tray cable is sunlight, heat, and moisture resistant and adheres to UL specifications. Both 300V and 600V tray cables are tested to meet the same flammability standards.

When should you use an exposed-run (ER) tray-rated cable?

Unlike standard tray-rated cables, exposed-run tray-rated cables can be installed in applications where the cable will drop from tray to tray or from tray to equipment, like a motor. These cables can be installed outside of the cable tray for six feet at a time for up to 50 feet with proper support, like with struts. In some applications, this reduces the need to protect non-ER cable in conduit when it runs between the tray and the device since they comply with the crush and impact requirements of armored cables. This eliminates the cost of conduit and installation, additional armor, and a hefty NEC violation fee.

What is a power limited tray cable?

Power limited tray cables can be routed in the same tray as 600V power and control tray cables when separated by a divider.

What type of cable is used for 600V?

Type TC ( Tray Cable) tray-rated cables will be the most common type you will see on the market. These are rated to 600V, and there are no length restrictions during installation. These cables are most commonly used in power and control circuits and in tray applications where flame retardant properties are required. They can be installed in raceways, cable trays, and in outdoor applications. If you intend to install a 600V tray-rated cable with slack between the tray and a piece of equipment for more than 6 feet, be sure to use a Type TC-ER (Tray Cable- Exposed Run) tray cable like ÖLFLEX® TRAY II, ÖLFLEX® Control TM/TM CY, ETHERLINE® TRAY CAT7, or ÖLFLEX® TRAY VTC.

How far can ITC cable be from tray?

The drop length for an ITC cable between tray and equipment cannot exceed 50 feet outside of the tray, even when supported.

Overview

Shielded

Unshielded

• ACTL Series and other UL 2808 Listed CTs
  The standard CT wires are unshielded, but have good noise rejection due to the twisting of the wires. Our standard twisted black and white CT wires are available in 100 foot (30 m) coils, see the CT Wirepage for details. CCS uses wire with the following specifications: Current Transform…
• Alternates
  These unshielded cables should be more readily available.

See more on ctlsys.com

Splicing

Signal Attenuation

Effect of interference Or Crosstalk