Tech. Explanations - Kendrion Binder

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the technical background Fig. 8 Overvoltage protection for solenoid by means of diode and Zener diode D Z = Zener diode U Z = Zener voltage U = supply voltage to solenoid 6.3.2 Measures for shortening response time and increasing linear force during response phase, and for reducing power consumption Solenoids permit the following options in special cases when the response time is to be shortened and the linear force increased during the response phase, or the power consumption is to be reduced. 6.3.2.1 Fast energisation and overvolting to shorten the response time t 1 Here, either the time constant governing the rise in current should be decreased (fast energisation) or the quotient increased for the same time constant (overvolting). L M Fast energisation: T = ——— R V + R M Overvolting: U —— RM 6.3.2.2 Overvolting to increase holding force The overvolting option mentioned above is also suitable for special situations requiring a higher linear force throughout the travel (during the response phase). KENDRION can supply suitable overvolting rectifiers which are in a position to supply the solenoid with a higher voltage throughout the response time. Besides shortening the response time to 30-40% of the standard value, such rectifiers also increase (by up to two times) the linear force during the response phase (for devices with 100% duty cycle) (Fig. 12). KENDRION single-phase overvolting rectifiers automatically switch back from the higher voltage to the standard voltage after the response phase. The higher power consumption during the brief overvolting time is normally no problem for the solenoid. Fig. 9 Overvoltage protection for switch by means of diode and ohmic resistance R V R M L M U = series resistor = ohmic resistance of solenoid = inductance of solenoid = supply voltage to solenoid M Fig. 10 Overvoltage protection for switch by means of capacitor and ohmic resistance R s = ohmic resistance C = capacitor D = diode R M = ohmic resistance of solenoid In the fast energisation option, connecting an ohmic resistance in series with the solenoid increases the total resistance and decreases the time constant. In the overvolting option, a multiple of the rated voltage is applied to the solenoid and this shortens the switch closing time for the same time constant T as when connected to the rated voltage. Fig. 11 illustrates how fast energisation and overvolting influence the response time t 1 . The values given are typical values for guidance only. Fig. 12 Influence of overvolting on the characteristic response of the solenoid a b c W 1 W 2 F M s = with normal energisation = holding force with normal energisation = with overvolting rectifier = normal linear work = additional linear work gained due to overvolting = magnetic force = solenoid travel Fig. 11 Shortening of response time by means of a) fast energisation and b) overvolting t 1N U N = closing time without shortening influences = rated voltage of solenoid 10 www.kendrionmt.com
the technical background 6.3.2.3 Economy mode to reduce power consumption It is not always necessary to increase the linear force during the response phase (see 6.3.2.2). There are applications in which the holding force achieved at the end of the response phase permits a decrease in the power consumption and hence also the temperature of the solenoid. Fig. 13 shows a circuit for such an economy mode. Here, once the plunger has reached its end position, a switch is actuated to connect a resistor with the solenoid in series. This resistor is shortcircuited by the switch during the response phase. This results in the following designations: plunger in initial position and during response time P 1 = U · I 1 = I 2 1 · R M Plunger in end position with power reduction P 2 = U · I 2 = I 2 2 · (R M + R V ) U R M I 2 = ——— = I 1 · ——— R M + R V R M + R V P 1 = input power s 1 R M = resistance of energisation coil R V = series resistor R V can be designed with a value of up to two times the resistance of the solenoid. (The exact value must be determined by experimentation.) Fig. 14 shows the magnetic forces for various input powers. 6.4 Input power and ambient temperature The input power values specified on the product data sheets were determined for an ambient temperature of 20°C. However, the energisation coils designed for this temperature can be operated in ambient temperatures up to 40°C. In doing so, the maximum permissible long-term temperature for the insulation used as given in DIN VDE 0580 point 3.3 Tab. 1 is reached, but not exceeded. The specified values for magnetic force and linear work are reached at the operating temperature and 90% of the rated voltage. The operating temperature is the temperature during operation with the specified data, increased by the reference ambient temperature of +40°C. The input power must be reduced for ambient temperatures higher than 40°C. This also reduces the linear work. In certain circumstances this also applies when the solenoid is fitted to part of a machine that reaches operating temperatures higher than 40°C. The reduction in the input power can be achieved by way of a special energisation coil or by operating the solenoid with a lower voltage. Fig. 15 shows the rated voltage, rated input power and rated linear work in relation to the ambient temperature for a DC solenoid. input power adjusted to suit the ambient temperature. For a guaranteed ambient temperature < 40°C, the input power and hence also the linear work can be higher than the corresponding rated value. 6.5 Switching operations for DC solenoids The oscillograms shown in Figs 16 and 17 indicate the typical current, voltage and solenoid travel conditions for a DC solenoid in relation to time t when being switched on and off. The two diagrams clearly show the different behaviour depending on whether switching is carried out on the DC or the AC side. The response times specified on the product data sheets are reliably achieved at 70% of the rated magnetic force and at rated voltage with the solenoid at its operating temperature. Fig. 16 Switching behaviour with switching on DC side Fig. 13 Circuit for economy mode M Fig. 14 Magnetic forces and holding forces for various input powers P Fig. 15 Operating modes for DC solenoids in relation to ambient temperature ϑ 13 = ambient temperature U N = rated voltage W N = rated linear work = rated input power P N Line 1 shows the voltage (in %) in relation to the ambient temperature with which a solenoid may be operated when its energisation coil is designed for the normal ambient temperature (as given on the product data sheet). Line 2 shows the permissible input power as a percentage of the specified value when the solenoid must be operated in an ambient temperature other than 40°C. Line 3 shows the linear work of the solenoid for an Fig. 17 Switching behaviour with switching on AC side ED= coil ON time I = current U = voltage s = solenoid travel t = time t 1 = response time t 11 = response delay t 12 = travel time t 2 = release time t 21 = release delay t 22 = return time www.kendrionmt.com 11
Page 1 and 2: BINDER W= F(s)ds ∫s2 W 1Ω =1—
Page 3 and 4: contents 1 2 2.1 2.2 2.3 2.4 3 3.1
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Page 9: the technical background Insulation
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Page 17 and 18: the technical background The workpi
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Tech. Explanations - Kendrion Binder

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