Switches double pole

The current-mode controlled forward converter has one additional consideration there is a double pole at one-half the operating switching frequency. The compensation bandwidth normally does not go this high, but it may cause problems if the closed-loop gain is not sufficiently low enough to attenuate its effects. Its influence on the control-to-output characteristic can be seen in Figure B-14. 

Newman and Lerner (N2) have used an arrangement where the signal picked up by a microphone attached to the flat surface below the orifice plate is amplified and fed to a loud speaker. The amplified bubble signal is then fed to one pair of fixed contacts of a double-pole double-throw switch of which the other pair of fixed contacts is connected to an audio-frequency generator. The movable contacts of the switch are connected to the vertical and ground terminals of an oscilloscope. This arrangement permits the observation of either the bubble signal or the sine wave as a function of the internal linear time-base of the oscilloscope. 

Figure 25.4 Block diagram of an apparatus for controlled-current coulometry. A double-throw, double-pole switch is used to turn the timer and electrolysis current on and off. [Adapted from G.W. Ewing, in Am. Lab. 13(6) 16-22 (1981). Copyright 1981 by International Scientific Communications, Inc.]...

Some of the standard arrangements include the single-pole single-throw (SPST), single-pole double-throw (SPDT), and the double-pole double-throw (DPDT) designs, but units are available with up to four poles. These switches... 

Fig. 1-36. Reflux-ratio timer. Ri, 3-megohm potentiometer R , 250,000-ohm J-watt Ra, 1-megohm potentiometer Rt, 50,000-ohm -watt Ci, 4-mfd. paper, 400 volts Cl, 2-mfd. paper, 400 volts Ct, C<, 8-mfd. electrolytic, 250 volts Vt, Fa, 117L7/M7GT Ry 1, Ry 2, double-pole double-throw relays, 1,000— 4,000-ohm coil Pi, Pa, 115-volt pilot lights X, standard receptacle (output) Si, Sa, single-pole single-throw switches. (Courtesy of Dr. H. Fischer and Analytical Chemistry.)...

Where possible the control of lighting fittings should be from a non-hazardous area, i.e. one adjacent to the hazardous area, using double pole switches. The supply neutral should be switchable. In rare situations this may not be practical in which case a switchboard or distribution board suitable for the hazardous area and the environmental conditions will need to be installed e.g. Zone 1, 1P55 or 56, with a suitable gas group and temperature class, see Chapter 10. 

The K Reactors are equipped with double pole> single throw switches which are connected Into Individual row and column tripping circuits using two relays In series per circuit ... 

Ceiling outlet with pull PS switch S2 Double-pole switch... 

Auto-transformers, which may be used to supply variable voltages to heating devices, may be cormected in such a way that either outlet line may be high with respect to ground. They should be purchased with a switch which breaks the connection of both outlet sockets to the power input line, or they should be rewired with a double-pole power switch to accomplish this. 

A double-pole disconnect device (switch, breaker, other) should be used and should disconnect both poles simultaneously. In some products a single-pole device may be allowed to disconnect only the phase conductor when the neutral can be verified, but this is often not possible since plugs are reversible in many EU countries, such as in Germany. Parts that remain live after the disconnect device is opened (OFF) shall be guarded against accidental contact by service personnel and a warning label is necessary adjacent to the hazard areas. 

Power disconnect Double pole switch, circ brkr, cord plug, other ... 

Input Plug Double-Pole Switch Output Receptacle... 

Double-pole switch providing means of isolation and switching... 

Isolation at the consumer s service position can be achieved by a double-pole switch which opens or closes all conductors simultaneously. On three-phase supplies the switch need only break the live conductors with a solid link in the neutral, provided that the neutral link cannot be removed before opening the switch. 

Therefore, immersion heaters must be wired on a separate radial circuit when they are connected to water vessels which hold more than 15 litres. Figure 3.55 shows the wiring arrangements for an immersion heater. Every switch must be a double-pole (DP) switch and out of reach of anyone using a fixed bath or shower when the immersion heater is fitted to a vessel in a bathroom. 

Figure 3.71 Flameproof fittings (a) flameproof distribution board (b) flameproof rectangular junction box (o) double-pole switch (d) flameproof inspeotion bend...

If it was a DPDT type (double pole, double throw), then there would be two switches hooked together mechanically, so two movable parts would simultaneously make contact with two upper terminals, or else with two lower terminals. Thus there would be 6 terminals altogether. At any rate, we will use no real switch at all, just a loose clip lead. 

Post-World War II installations will usually have a consumer unit, which is a small distribution board with a double pole isolating switch and a phase busbar to feed the fuses or MCBs controlling the final circuits. There will be terminal blocks for the neutrals and protective conductors. The earth terminal block may be utilised as the consumer s earthing terminal. Some of the older models may have wood frames and/or may be backless. As BS 7671 requires connections to be made in non-flammable enclosures, the wooden framed type do not comply and the backless ones are acceptable only if mounted on non-flammable material. If rewirable fuses to BS 3036 are used, check that the correct size of fuse wire has been used. For cartridge fuses, check that blown fuses have not been repaired with a bit of fuse wire spanning the contacts or the cartridge replaced by a nail, hairpin or the like. There should be only one final circuit connected to each fuse carrier or MCB. 

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