Cables maximum length

Cables between the SPD and equipment shall be done by shielded cable (maximum length Im) properly earthed at the ends or the ordinary cable can be used when the same run through properly earthed (at both ends) metallic conduit. 

Most computers built after 1997 have one or two flat ports in place of one DB-9 serial port. These ports are Universal Serial Bus (USB) ports and they are used for connecting multiple (up to 127) peripherals to one computer through a single port (and use of multi-port peripheral hubs ). USB supports data transfer rates as high as 1.5MBps. Additionally, USB cables can be a maximum length of 5 meters. 

In addition to running the cable(s) correctly, it is important that you realize that you are limited to the number of devices you can have on the SCSI channel as well as the maximum length of the SCSI bus. Generally speaking, the faster the SCSI, the shorter the total length of the bus. 

Type of final circuit Cable size (twin and earth) MCB rating. Type B (A) Maximum floor area covered by circuit (m ) Maximum length of cable run (m)... 

I,// 2 =//f = maximum resistance of the connecting leads from the CT terminals to the relay terminals. For calculating this, for an estimated length and size, refer to cable data in Table 13.15... 

Polymer cable anodes are made of a conducting, stabilized and modified plastic in which graphite is incorporated as the conducting material. A copper cable core serves as the means of current lead. The anode formed by the cable is flexible, mechanically resistant and chemically stable. The cable anodes have an external diameter of 12.7 mm. The cross-section of the internal copper cable is 11.4 mm and its resistance per unit length R is consequently 2 mQ m l The maximum current delivery per meter of cable is about 20 mA for a service life of 10 years. This corresponds to a current density of about 0.7 A m. Using petroleum coke as a backfill material allows a higher current density of up to a factor of four. 

Two UV detectors are also available from Laboratory Data Control, the UV Monitor and the Duo Monitor. The UV Monitor (Fig.3.45) consists of an optical unit anda control unit. The optical unit contains the UV source (low-pressure mercury lamp), sample, reference cells and photodetector. The control unit is connected by cable to the optical unit and may be located at a distance of up to 25 ft. The dual quartz flow cells (path-length, 10 mm diameter, 1 mm) each have a capacity of 8 (i 1. Double-beam linear-absorbance measurements may be made at either 254 nm or 280 nm. The absorbance ranges vary from 0.01 to 0.64 optical density units full scale (ODFS). The minimum detectable absorbance (equivalent to the noise) is 0.001 optical density units (OD). The drift of the photometer is usually less than 0.002 OD/h. With this system, it is possible to monitor continuously and quantitatively the absorbance at 254 or 280 nm of one liquid stream or the differential absorbance between two streams. The absorbance readout is linear and is directly related to the concentration in accordance with Beer s law. In the 280 nm mode, the 254-nm light is converted by a phosphor into a band with a maximum at 280 nm. This light is then passed to a photodetector which is sensitized for a response at 280 nm. The Duo Monitor (Fig.3.46) is a dual-wavelength continuous-flow detector with which effluents can be monitored simultaneously at 254 nm and 280 nm. The system consists of two modules, and the principle of operation is based on a modification of the 280-nm conversion kit for the UV Monitor. Light of 254-nm wavelength from a low-pressure mercury lamp is partially converted by the phosphor into a band at 280 nm. 

Ethernet and real-time applications. Because of the random access method used there is no guaranteed response time within an Ethernet LAN. All nodes have equal priority for getting access to the physical cable. Due to the Ethernet specifications the maximum uninterruptable length of a block of data on the cable is 1500 bytes, corresponding to a transfer time of 1.2 ms. If data, e.g. from an active experiment, is to be transferred in real-time, delays in the order of milliseconds must be tolerable. This should not be a problem, if data can be buffered in local memory of the nodes. If strict timing for the synchronization of processes on... 

The IEEE 802.3 specifications describe rules for the maximum number of repeaters that can be used in a configuration. The maximum number of repeaters that can be found in the transmission path between two nodes is four. The maximum number of network segments between two nodes is five, with a further restriction that no more than three of those five segments may have other network stations attached to them (the other segments must be interrupter links which simply connect repeaters). These rules are determined by calculations of maximum cable lengths and repeater delays. Networks that violate these rules may still be functional, but they are subject to sporadic failures or frequent problems of an indeterminate nature. Bridges are recommended for networks where many repeaters are required they can limit the amount of traffic on each segment and improve performance. 

Almost every computer made since the original IBM PC has at least one serial port. They are easily identified because they have either a DB-9 male (shown in Figure 2.24) or DB-25 male port. Standard serial ports have a maximum data transmission speed of 57KBps and a maximum cable length of 50 feet. 

What is the maximum practical length of a standard parallel printer cable ... 

Each type of cabling has its own benefits and drawbacks. Table 8.2 details the most common types of cabling in use today. As you look at this table, pay particular attention to the cost, length, and maximum transmission rates of each cabling type. 

Repeaters are very simple devices. They allow a cabling system to extend beyond its maximum allowed length by amplifying the network voltages so... 

Equation (9.3) can be used to determine the maximum route length that can be accepted for a) and b) above. Usually two different values of route length will be obtained and the shortest should be taken for selecting the cable size. Equation (9.3) can be transposed to find the route length as follows,... 

Find the smallest cable size and its maximum route length to satisfy a running volt-drop of 5% and a starting volt-drop of 15%. Choose an XLPE insulated 600/1000 V 3-core cable to be routed in air. The ambient air temperature is 25°C. 

The value of X depends upon the route length and the maximum amount of power that is ever likely to be continuously transferred under normal conditions (for example, it may be decided to size the cable to handle the rated power output of one generator on one of the platforms). 

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