Resistances

Special resistors are resistors which act as a factor analog sensors or agent such as temperature, light, voltage, etc.These agents cause a variation of the ohmic resistance value by varying the magnitude of which is controlling agent resistance.These resistors are formed of materials that vary its ohmic value or when the agents are controlling factors vary, but this variation in the ohmic value of this resistor is nonlinear with respect to the change in value of the agents being measured.Special types of variable resistors used are detailed further below.

Variable resistors with temperature (NTC - PTC)

These special strengths known as NTC and PTC stands for Negative Temperature Coefficient Positive Temperature Coefficient and its ohmic value varies depending on the temperature you have in your environment.The difference between NTC and PTC is the NTC resistance decreases with increasing temperature to which they are subjected. However the PTC resistance increases with increasing temperature to which they are subjected.It has many industrial applications such as thermostats, controlling short-circuit monitoring the temperature increase with increasing current flowing somewhere near the variable resistance by temperature. One application where've seen it work is to control activation of fans that turned the air flow passing through the resistance varying its value on cooling sending a signal to be within a circuit acting as a thermostat.The characteristic curve of the PTC and NTC are nonlinear temperature may have sections that do not fulfill their indicated function and has another temperature zone that starts at the switching temperature the resistance value increases or decreases as indicated by the type resistance. After a certain temperature, the resistance returns to stop controllably vary resistance. It is indicating that the resistance has a range of temperatures.

With light variable resistors (LDR)

These variables are light LDR resistances corresponding to the acronym of Light Dependent Resistor, they are also known as fotorresistor.These resistors are built with materials that are in darkness and high ohmic value when receiving light it increases its conductivity reducing its ohmic value. They are used to activate lighting at night to detect the passage of objects causing the object to block the light LDR resistance.

Variable resistors with voltage (VDR)

The VDR are voltage dependent resistors as indicated by its acronym Voltage Dependent Resistor.These resistors do not have polarity, but their use is specified by the manufacturer for a particular voltage and current.Its main use is usually contacts or circuits to protect against sparks or surges.Identifying the characteristics of the VDR may be by colored rings or a colored dot.In the case of the color point criteria table that follows.

If they are marked with colored circles have three or four colored rings which indicate the intensity and voltage.The first ring counting from the opposite side to the terminals indicates the intensity will be 1mA if orange, red and 10mA if 1oomA if brown.

Characteristics and applications of resistances

A resistor or resistor is an element which causes opposition to passage of current, causing a difference in terminal voltage (a voltage) appears.

There are various kinds of industrial electric heaters that have a wide application, among which are:

Cartridge resistance high-densityTypical applications: Mainly to be inserted into a borehole in a solid metal, localized heating processes that require rigorous temperature control such as molds, cylinders, labeling, hot stamping, sealing bags, packaging and medical equipment, extruders and injection molding for plastic Likewise for heating gases and liquids.

Features: High Density Resistors (Compacted) for high temperature applications where reduced durability of the cartridges are a constant problem. High density cartridges last up to 15 times more in the same application as common cartridge resistors. They are also capable of providing up to 5 times higher densities of electrical power with temperatures up to 1500 F (820 C). Multiple endings to protect cables against bending, moisture, abrasion, contamination and for special applications.

Cartridge resistance low density

Typical applications: Mainly to be inserted into a borehole in a solid metal conductor of heat for localized heating processes that require rigorous temperature control, such as packaging machines hot and labeling, stamping equipment, adhesive guns injected plastics and waxes. Also for heating gases and liquids and other low temperature applications.

Features: cartridge resistance Low Density Applications are inexpensive low and medium temperatures, with maximum temperature of 1200 F (650 C) and power densities of 30-45 W / in2. Multiple endings to protect cables against bending, moisture, abrasion, and special applications pollution. Many sizes or power ratings available or custom-made.

Resistors band isolated with mica

Typical Applications: Used in operations requiring heating of cylindrical surfaces such as cannons plastic extruders, injection and blow molding machines, plastics, storage tanks, barrels, containers for heating foods, autoclaves and blow molding equipment.

Features: The locking mechanism isolated resistors tape is a unique feature that is built-low thermal expansion clamp that clips to better separate clamps or bent flanges ("ears"). The design of the resistors used for applications up to 1200 F (650 C) and power densities of up to 45W / in2 7W / cm2. The basic construction designs are units of one or two expandable clamps with various arrangements for screw terminals and flexible cables. Holes or cuts made to order. Many sizes and power ratings available or custom-made.

Tubular resistors

Typical applications: The most versatile and widely used resistance in industrial, commercial, scientific and military, such as combined radiation and convection heaters, introduction holes drilled or milled slots in plates or molds molten metal and subjected to pipeline applications. Also for heating by direct immersion fluid.

Features: The design of the tubular heating elements produces a unique robust and durable heater resistance against shock, vibration, corrosion and high temperatures. They can be formed in an unlimited variety of shapes to welded with silver and steel, brass, stainless steel or exotic piece of metal parts and metal castings. Standard materials of the tube are copper, stainless steel and colorless with various diameters and screw arrangements with flexible cables or seals, connections and flanges.

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