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Calculation of power of a heater

Change of electrical power of a heater depending on temperature

          Applet for build-up of system of nomograhic charts for calculation of electrical power (developed quantity of heat) a conductor (heater) [W=J/s].

          Applet for build-up of system of nomograhic charts for calculation of electrical power (developed quantity of heat) a conductor (heater) [cal/s].

          Specific resistance of a wire (heater) calculated under the formula:

                          at substitution of value of temperature in oC      Rs = R0 [1+a (T-20)],                             [1]

                          at substitution of value of temperature in K       Rs = R0 [1+a (T-293)],                           [1]

where

R0 specific electrical resistance at temperature 20oC, Ohm sm [104 Ohm sm = Ohm mm 2 / m];

a a resistance temperature coefficient, 1/oC [1/K];

T wire temperature, oC [K].

         Electrical resistance of a site of a wire pays off under the formula:

R = Rs L / S,                               [2]

where

L wire length, sm [m];

S a wire sectional area, sm2 [mm2].

          Electric heater power [W] is calculated as follows:

P = U2 / R,                                    [3]

where

U voltage, V;

          Quantity heat imparted to the wire q = P [ J/s ]

          The circuit design of nomographs is presented in drawing 1.

                            Drawing 1. The circuit design of system of nomographs

         After applet start an auxiliary window will have the following appearance (drawing 2).

                           Drawing 2. An additional window of an applet on build-up of system of nomographs

         In an auxiliary window the circuit design of disposing of nomographs is already shown, but she demands recurring feeding into, therefore on each small square which is marking out a nomograph "is clicked" by the right key of the mouse and the left key "clicked"on that place where there should be a colour flag indicator (a place of disposing of meaning of parametre Z of a nomograph). It is possible choose any other location of variable parametre Z. After recurring appointment of the circuit design of nomographs "is clicked" by the left key of the mouse on sign "[-]", had in left overhead to the angle of the circuit design of nomographs. It will change the aspect on "[+]". It means, that the circuit design of nomographs is fixed. .

  Drawing 3. An additional window of an applet on build-up of system of nomographs with the tuned circuit design of nomographs

          After attaching of the circuit design of nomographs, "is in succession clicked" on everyone sign, marking out a nomograph, and it is pushed three buttons "In the working memory" (" "), "Substitution ID" (" "), "the Total formula" (" ") for entering of all parametres of a nomograph into an on-line storage and design formula formation.

          We transfer to the basic window and we induct meanings of steps on axes "X" and "Y". We push the button "to Build on ID" (" ").

       Drawing 4. The basic window of an applet for build-up of system of nomographs.

          More detailed instruction on operation with an applet.

          Applet for build-up of system of nomograhic charts for calculation of electrical power (developed quantity of heat) a conductor (heater) [W=J/s].

          Applet for build-up of system of nomograhic charts for calculation of electrical power (developed quantity of heat) a conductor (heater) [cal/s].






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