June 11, 2023
Wire and cable definitions
Products with few strands, small diameter and simple construction are called wires, products without insulation are called bare wires, and others are called cables. >;A larger conductor cross-sectional area (more than 6 square millimeters) is called large wire, and a smaller one (less than or equal to 6 square millimeters) is called small wire insulated wires are also called wires.
Wires and cables mainly include bare wires, magnetic wires and insulated wires for electrical appliances, power cables, communication cables and optical cables.
The difference between low current cables and low current cablesDifference between SYV and SYWV: SYV is a polyethylene insulated video transmission line. SYWV is an RF transmission line with foam physical insulation. for cable TV.
Difference between PBC and PBV 2-wire: PBX is a twisted two-wire PB wire without an outer sheath and is used for broadcast connection. Two-core RVV wires are laid directly in cables, with an outer sheath, used for power supply, control signals, etc.
The difference between RVV and KVV RVVP and KVVP: The wires used in RVV and RVVP are flexible wires consisting of several strands of thin copper wires, that is, RV wires. The wire used in KVV and KVVP is a rigid wire consisting of one thick copper wire, that is, BV wire.
Difference between AVVR and RVVP: AVVR refers to unshielded cable with wire diameter less than 0.5mm, while RVVP refers to shielded cable with wire diameter greater than or equal to 0.5mm.
Naming rules for low current cables
1. Content included in product name
(1) Product use case or size class name
(2) material or type of product design;
(3) Important or optional product features
The names are mostly in above order, sometimes to emphasize important or additional features, features are written before or before corresponding description of structure.
2. Structure description order
The structure of product is described from inside out: conductor --> insulation --> inner sheath --> outer sheath.
3. Simplify
In absence of confusion, some structure descriptions have been omitted or abbreviated.
Example:
SYV75-5-1(A, B, C)
S: RF Y: Polyethylene insulation V: PVC sheath A: Series 64 B: Series 96 C: Series 128 75: 75 ohm 5: Wire diameter 5mm 1: Solid
SYWV75-5-1
S: RF Y: Polyethylene insulation W: Physical foaming V: PVC sheath 75: 75 Ohm 5: Cable outer diameter 5 mm 1: Solid
RVVP2*32/0.2
/p>ZR-RVS2*24/0.12
ZR: flame retardant R: soft wire S: twisted pair 2: 2-core stranded wire 24: 24 copper wires per core 0.12: diameter of each copper wire 0.12 mm< /p > Composition of low current cables
From inside to outside, it consists of an inner conductor, an insulation, an outer conductor, and a sheath.
Inner conductor: since attenuation is mainly caused by resistance of inner conductor, it has a big impact on signal transmission
Isolation: Affects attenuation, impedance, return loss, and other properties
Outer conductor: loop conductor, shielding function
Cable code valueRVVP: Flexible cable with copper core, shielded with PVC insulation and PVC sheath, voltage 300V/300V, 2-24 cores. Application: instruments, meters, intercom, monitoring, control plant.
KVVP: PVC braided shielded cable Application: signal transmission, control, measurement of electrical appliances, appliances, power distribution devices
SYWV(Y), SYKV CATV, Broadband Dedicated Cable Structure: (coaxial cable) single anaerobic round copper wire + physical polyethylene foam (insulation) + (tin wire + aluminum) + polyvinyl chloride (polyethylene)
PVC flexible cable RVVApplication: Household appliances, small power tools,instruments and power lighting
AVVR PVC installation flexible cable
Cables with PVC insulation RV, RVP
RVS, RVB are suitable for connecting cables of household appliances, small power tools, appliances, meters and power lighting
PVC insulated cables BV, BVRApplication: suitable for electrical appliances and fixed power lighting wiring
Low current cable selection example1. Video Cable: If distance from camera to monitoring host is ≤200 meters, please use SYV75-3 video cable; if distance from camera to monitoring host is > 200 meters, use SYV75-5 video cable.
Digital video surveillance, transmission from camera is carried out over twisted pair, such as cat5e, cat6, etc.
2. PTZ control line: if distance between PTZ and controller is ≤100 meters, use RVV6×0.5 shielded wire; if distance between PTZ and controller is >100 meters, please use PBB6×0.75 sheathed wire Set of lines. In practice, RVVP2*075 is usually used.
3. The lens control line uses an RVV4×0.5 sheathed line.
Selection of low current cables
Video transmission usually uses direct modulation technology in form of a baseband (bandwidth of about 8 MHz), and most commonly used transmission medium is coaxial cable; coaxial cable is specially designed for video signal transmission. , its frequency loss, image distortion and image attenuation are relatively small, and it can quite fulfill task of transmitting video signals.
As a rule, special coaxial cables of SYV75 Ohm series are used; SYV75-5 model is commonly used (video signal transmission length without relay is usually 300-500m); for long distances, SYV75-7 and SYV75 cables are used. -9 coaxial cable is required (in real life, repeatable transmission distance of a thick cable can reach more than 1 km).
Communication cables are commonly used in cameras equipped with motorized pan/tilt and motorized lenses, and remote control decoders must be installed on site when used; The data cable between them usually has 2 core shielded communication cable (RVVP) or 3 kinds of UTP twisted pair cable, cross-sectional area of each core is 0.3mm2 ~ 0.5mm2; larger, basic communication distance specified for RS-485 communication is 1200 m, but in real engineering, use of PBB2-1.5 sheathed wire can increase communication length to more than 2000 m.
Control cable is typically a stranded cable used to control gimbal and motorized adjustable lens; one end of control cable is connected to controller or control terminal of gimbal and motorized lens of decoder, and other end is directly connected to corresponding pan/tilt and electric lens terminals; control cable provides DC or AC voltage, and distance is generally very short (sometimes less than 1m), basically there is no interference problem, so there is no need to use shielded wires.
Most commonly used control cables use 6-core or 10-core cables, such as RVV6-0.2, RVV10-0.12; The 6-core cables respectively connect to top, bottom, left, right, auto, and public pan/tilt terminals. In addition to 6 terminals connected to pan/tilt, 10-core cable also includes 4 terminals for zoom, focus, iris and a common electric lens; in monitoring system, control cable from decoder to pan/tilt and lens due to generally relatively short distances, there are no special requirements, while distance from controller in central control room to pan/tilt and electric lens ranges from tens of meters to hundreds of meters, certain requirements are imposed on control cable, that is, diaa meter of cable must be thick, such as RVV10-0.5, RVV10-0.75.
Audio monitoring cables generally use 4-core shielded communication cables (RVVP) or Category 3 UTP twisted-pair cable, and each core has a cross-sectional area of 0.5mm2. The sound signal of control head in monitoring system is transmitted to central control room using a point-to-point wiring that is transmitted with high voltage and low current, so an unshielded 2-core cable such as PBB2-0.5 is sufficient.
The cables RVV2*0.3 (signal line) and RVV4*0.3 (2-wire signal + 2-wire power cable) are usually used between external detector and alarm controller; alarm controller and terminal 2-wire signal lines are commonly used between security centers.
Shielded wire or twisted pair for signal wire or ordinary sheathed wire should be specified according to product requirements of different brands; The thickness of signal wire depends on diameter of signal wire. controller and center distance and quality are determined; The power supply of alarm controller usually uses local power supply instead of centralized power supply in control room, and line is relatively short, usually using RVV2×0.5” or higher. ; The power supply of perimeter alarm and other public alarm equipment is generally used in centralized power supply mode, and line is relatively long, generally with specifications above RVV2 * 1.0".
Building intercom system Most of cables used are RVV, RVVP, SYV and others, which can transmit voice, data, video images, and cable requirements also affect voice quality, transmission speed data quality and speed video transmission, etc.; voice and alarm cables mainly use RVV4-8*1.0 cables; SYV75-5 cables are used for video transmission, some systems are afraid of external interference or cannot be grounded, and cables used in system must use RVVP cables.
Line Standard of Direct Pushbutton Video Intercom System:
The video, audio talkback and remote release connectors of each indoor unit are connected to call station in parallel with bus, but each call line is connected to call station separately directly; coaxial video cables SYV75-5 , SYV75-3 4-core unshielded or sheathed shielded wire (AVVR4, RVV4 or RVVP4, etc.) for microphone/speaker/unlock, 2-core shielded wire (AVVR2, RVV2, etc.) .) for power cord 2-wire for call line Screened wire (RVVP2).
Visual intercom system:
Main line includingNo coaxial video cables (SYV75-5, SYV75-3, etc.), power lines (AVVR2, RVV2, etc.), audio/data control lines (RVVP4, etc.), home alarm lines (RVVP6, etc.).
