The representation method and function of cement resistance

The indication method of cement resistance is specified as follows, according to GB T2691.

5W2R2J—power 5W, resistance value, allowable deviation 5;

7W27RJ—power 5W, resistance value 27, allowable deviation 5;

5WR1F—power 5W, resistance value, allowable deviation 1; (The symbol for this should be 5WR10F).

The function of the cement resistor is as follows, 1: the function of power supply current limiting, usually connected at the main voltage +300V and the E pole and C pole of the power switch, the function is that the power supply will not be washed out and damaged by the power supply.

2: Power supply starting resistor, power tube and starting circuit across the resistance between +300V, its voltage drop and current are larger, so the cement resistor with larger power is also used.

3: The peak pulse absorption circuit between the poles of the power switch tube B, C and E is also a high-power cement resistor, which also protects the power switch tube.

4: The current protection circuit is generally connected between the power switch E pole and the ground, and its resistance can be ignored when it works normally, because the resistance value of its resistance is very small and there is no current, only when the circuit itself is short-circuited with the load, the current of the E pole of the power switch tube can be increased, so that the two ends of the resistance produce a protection voltage to start the related circuit.

According to GB T2691.

5W2R2J—power 5W, resistance value, allowable deviation 5;

7W27RJ—power 5W, resistance value 27, allowable deviation 5;

5WR1F—power 5W, resistance value, allowable deviation 1; (The symbol for this should be 5WR10F).

The role of cement resistors in speaker crossovers:

1, Attenuation;

2. Form an impedance compensation network with capacitors.

The resistance value of cement resistors is generally marked on it, and it is generally a high-power resistance, from a few watts to hundreds of watts, which is used in industry!

The specification of cement resistance is marked as follows, according to the provisions of 5W2R2J, the power is 5W, the resistance is this value, and the allowable deviation is plus or minus 5%. 7W27RJ, power 5W, resistance value 27, allowable deviation plus or minus 100 percent wide silver five. 5Wr1F, power 5W, resistance value, allowable deviation which Qiaoxun plus or minus one hundredth.

The role of cement resistors:

The function of power supply current limiting is usually connected at the main voltage of 300V and the E pole and C pole of the power switch, and the function is that the power supply will not be washed out and damaged by the power supply. The power supply starting resistor, the power tube and the starting circuit are connected to the resistance between the positive 300V, and the voltage difference and current are large, so the cement resistor with higher power is also used. The peak veins between the poles of the power switch tube B, C and E.

The cement resistor plays the role of a resistor that limits the starting resistance of the motor in the circuit and replaces the resistance of the load output.

This is a kind of "fire mud", also called refractory mud, with this refractory material to encapsulate the resistor, it is mainly composed of resistance wire (wire wound or metal oxide film) core, packaging filler, solder lead wire and ceramic shell, etc., some of the external metal bracket, cement resistance packaging generally has horizontal and vertical two.

The main features are as follows:

1. The volume is larger than other resistors, and there are generally two kinds of packages: vertical and horizontal;

2. High power, the common power is 1W, 2W, 5W, or even hundreds of watts, and the current resistance is large;

3. The resistance range is wide, but most of them are only within 100 ohms;

4. The accuracy is generally not high, due to the serious heat generation of the power, the thermal stability is not very good, the general accuracy is 2%, 5%, 10%, etc.;

5. Good temperature and heat resistance, good damp heat resistance, high insulation, no combustion, etc.

The cement resistor is made by winding the resistance wire on the non-alkaline heat-resistant porcelain, and adding heat-resistant, moisture-resistant and corrosion-resistant materials to protect and fix it, and put the winding resistor body into the square porcelain frame, and fill and seal it with special non-combustible heat-resistant cement. The outer side of the cement resistor is mainly made of ceramic. [This paragraph] features high power 20-50-100w replacement cement resistor.

1. Shock-resistant, moisture-resistant, heat-resistant, good heat dissipation, low ** and other characteristics.

2. Completely insulated, suitable for printed circuit boards.

3. The porcelain rod is wound and then welded to produce accurate resistance value and prolong life.

4. The high resistance value is made of metal oxide film body (MO) instead of winding.

5. Excellent heat resistance, small temperature coefficient of resistance, linear change.

6. Resistant to short-term overload, low noise, and the resistance value does not change over the years.

7.Good explosion-proof performance and protective effect. Cement resistors are usually used in occasions with high power and high current, with 2W, 3W, 5W, 10W or even greater power, such as air conditioners, televisions, and other electrical appliances with power above 100 watts, basically cement resistors are used.

The disadvantages of cement resistance are that it is large in size, high in calorific value when used, not easy to dissipate, and the precision often cannot meet the requirements of use, stability, etc. For those who require high power, small volume resistance, or high precision, fast heat dissipation, cement resistance can be replaced by Jepsun power resistor, 3W, 20W, 30W, 50W, 100W, and even the above power can be achieved, using TO-220, TO-247 package, high precision, strong stability, fast heat dissipation.

Cement resistance is the resistance that is potted with cement (in fact, it is not cement but refractory mud, which is commonly known);

Cement resistors are all resistors with higher power. It is able to allow the passage of large currents.

This is a metal film resistor, give you a cement resistor** to see for yourself.

Generally, the cement resistors are white and square, generally used for occasions with large power, so the volume is relatively large, and the color ring is not used to identify the size of the resistance.

The cement resistor is made by winding the resistance wire on a non-alkaline heat-resistant porcelain part, and adding heat-resistant, moisture-resistant and corrosion-resistant materials to protect and fix it, and put the winding resistor body into a square porcelain frame, and fill and seal it with special non-combustible heat-resistant cement. The outer side of the cement resistor is mainly made of ceramic (generally divided into high-alumina porcelain and feldspar porcelain).

There are two types of cement resistors: ordinary cement resistors and cement wirewound resistors. Cement resistor is a type of wirewound resistor, which is a resistor with high power and can allow a large current to pass through.

The function of the cement resistor is the same as that of the general resistor, but it can be used in the occasion of large current, such as connecting with the motor in series, limiting the starting current of the motor, and the resistance value is generally not prudent.

Cement resistors have the characteristics of large dimensions, shock resistance, moisture resistance, heat resistance, good heat dissipation, low quality, etc., and are widely used in power adapters, audio equipment, audio crossovers, instruments, meters, televisions, automobiles and other equipment.