US2841759A - Voltage regulator - Google Patents

Description

y 1958 w. s. SNYDER ET AL ,8

VOLTAGE REGULATOR Filed July 11, 1956 REVERSIBLE MOTOR I 52 4a I 7+- i 44 I 48 i 42 46 i 50 INVENTORS WILLIAM S. SNYDER FRED W. WILLARDSON BY W57,

ATTORNEY United States Patent VOLTAGE REGULATOR William S. Snyder, Emporium, and Fred W. Willardson, Smethport, Pa., assignors to Sylvania Electric Products Inc., a corporation of Massachusetts Application July 11, 1956, Serial No. 597,225

3 Claims. (Cl. 323-66) I This invention relates to voltage regulators, particularly to means for regulating the voltage of a direct current supply, although the voltage of an alternating current supply may be regulated by substantially the same mechanism.

It is an object of the invention to provide a simple means to maintain regulation of a supply voltage and within any desired voltage limits.

Other objects will become apparent after reading the following specification in conjunction with the accompanying drawing which exemplifies in wiring diagram form the principles of the invention.

Referring to the drawing in greater detail at there is shown a D.-C. supply circuit with regulator 12 therein to vary the voltage in the supply circuit. The regulating means is not shown since it forms no part of the invention and it may partake of many forms, as for example, a variable resistor in series in the D.-C. line or a variable resistor or variable transformer in the A.-C. supply to a voltage rectifier. However, the supply may be regulated, and which supply may even be an A.-C. supply, the leads are tapped at the regulator or at the load to enable the voltage to be sampled, and to apply the sampling voltage to mechanism to effect a change in the regulator should the voltage not be within a desired selected range. To simplify the disclosure the regulation is disclosed as that of a D.-C. circuit.

In accordance with this invention, therefore, the voltage is sampled, as by the leads 14 and for convenience one of the leads is grounded as at 16. The other lead is connected to one end of a switch 18 and one end of a resistor 20. The switch is a single pole two position switch in one of which it shorts out the resistor by contacting a contact 22 to which the other end of the resistor is connected and in the other of which it connects with a contact 24.

The contact 22 is connected via a variable resistance 26 and coil 28 of a primary relay to ground while the contact 24 is connected via another resistor 30 and coil 32 of a second primary relay to ground. The variable resistors 26 and 30 may be gauged together for convenience in attaining simultaneous adjustment of the resistors. All of the relays are diagrammatically illustrated as of the solenoid type but obviously they may be of any other type, as a pivoted armature or electronic type. The coil 28 controls the operation of a switch member 34 in turn operative to control the circuit to a secondary relay coil 36, the switch member and coil being in series in a circuit desirably, though not necessarily, independent of the circuit to be regulated and here shown as an A.-C. circuit. Likewise the primary relay coil 32 controls the operation of a switch member 38 in series with a secondary relay coil 40 also across the same line as the series connected switch member and coil 34, 36. Each of the coils 36 and 40 controls the equivalent of a single pole, double throw bar switch with the two double throw switches in series with each other and in series with a reversible motor across the A.-C. line, as shown.

In the form disclosed, the coil 36 controls the operation of two bridging bars 42 and 44, the bar 42 being closed against the contacts in line 46 only when the switch member 34 is open and the bar 44 being held against the contacts in line 48 only when the switch member 34 is closed. Likewise, the coil 40 controls the operation of two bridging bars 50 and 52, the bar 50 being held against the contacts in line 46 only when the switch member 38 is closed and the bar 52 being closed against the contacts in line 48 only when the switch member 38 is open. The conjoint action of the switches controlled by the coils 36 and 40 determines the direction of rotation of a reversible motor 54 in series with the A.-C. line and the bar switches, the motor being connected in any suitable fashion to the regulator to effect lowering of the sampled voltage when the line 46 is energized and to raise the sampled voltage when the line 48 is energized. Connected across the A.-C. line is a second motor 56 operative to drive a member 58 which periodically reciprocates the switch 18 between resistance short circuiting position and contact with terminal 24. The member may be a four lobed cam driven from a motor such as a synchronous clock motor to operate the switch in the order of two cycles per second.

Suitable switches such as 60 and 62 for the various supplies may be provided.

The functioning of the apparatus is as follows:

It should be remembered that the voltage of a relay required to pull up an armature such as that of relay 28, 34, is always greater than that required to maintain its armature or core in its pulled up position. Therefore, it is possible to maintain the contact member 34 in pulled up position even though the resistance 20 be inserted into the supply circuit to the coil 28, provided the voltage in the sampled line be high enough. The coil 32 is either in the circuit or cut off from the circuit completely, depending on the position of switch 18. The resistors 26 and 30 are so adjusted that when the regulated voltage is normal (i. e., neither higher than nor lower than a small amount above or below the intended value) coil 28 draws an amount of current which is slightly more than what is required to sufiiciently energize coil 28 to hold contact 34 open even with resistor 20 in series with the coil, and resistor 30 is adjusted so that coil 32 draws an amount of current slightly less than what is required to sumciently energize coil 32 to close contact 38. Assuming that the voltage in the DC. line is within the normal range-say, between and 154 volts, the switch member 34 will have been pulled up and maintained in pulled up position notwithstanding the periodic insertion of the resistor 20 into the circuit of the coil 28. On the other hand the switch member 38 will remain in open position since the pull up voltage under normal D.-C. line conditions is insufficient to sufficiently energize the coil. The coil 32 will be completely de-energized at each cycling of switch 18 by opening of the switch at contact 24. Therefore, operation of switch member 38, if operative at all, will be periodic. Under normal conditions, although the coil 32 is periodically energized, the switch member 38 remains in open position.

When the switch members 34 and 38 are open, bar 42 is closed on its contacts while switch bar 50 is open; therefore, no current flows to the reversible motor via the line 46. Likewise no current flows through the line 48 even though switch bar 52 is closed since switch bar 44 is open. Therefore, the regulator remains inoperative and ineifective to change the voltage in the D.-C. line.

Should the DC. voltage fall below the fall out level of relay 28, 34, as at 150 volts, the switch member 34 drops to closed position, the coil 36 becomes energized causing the switch bars 42 and 44 to move to their other positions. Since with low voltage the coil 32 is still ineffective to close the switch member 38, the switch barsSO. and 52 remain as they were. Therefore, a circuit to the motor is completed via line 48, effective to rotate the motor 54 to raise the voltage. Meanwhile, and at all times, the switch 18 is cycling fairly rapidly between contacts 22 and 24 and eventually the voltage in the D.C. line will be suflicient on opening of switch 18 with contact 22 to hold switch member 34 open, thereby maintaining coil 36 de-energized and maintaining the circuit to line 48 open at switch bar 44.

Should the voltage in the D.-C. rise to a level above the pull up voltage of relay 32, 38, as above 154 volts, the coil 40 will be energized, efiecting opening of switch bar 52 and closure of switch bar 50 on its contacts to establish a circuit to the motor via conductor 46 thereby causing the motor 54 to move in a direction to operate the regulator to lower the voltage. This lowering of the voltage will occur in steps since the coil 32 is only intermittently and periodically energized by reason of the periodic breaking of the D.-C. circuit at contact 24. Eventually, the voltage will be low enough, say below 154 volts, so that the coil 32 will be ineffective to pull up the switch member 38. Therefore the switch bars 50 and 52 will remain in the illustrated position and the circuit to the motor via line 46 will be opened. Since at this time the bar 44 is open, no current is applied to the motor 54 via line 48 and the motor 54 will remain static.

Having thus disclosed the invention, what is claimed as new is:

1. A voltage regulating system comprising a supply circuit whose voltage is to be regulated, a regulator effective to vary the voltage in that circuit, a mechanism to operate the regulator to cause it to raise or lower said voltage, a pair of secondary relays with their switch members in series relation connected to said mechanism, a pair of primary relays whose switch members control, respectively, the current flow in the coils of the secondary relays, each of the coils of said primary relays leading to contacts at one end of a double throw single pole switch whose other end is connected to one of the legs of the supply circuit, means for cyclically operating the double throw switch and a resistor shunting the switch.

2. A voltage regulating system comprising a supply circuit whose voltage is to be regulated, a regulator effective to vary the voltage in that circuit, a mechanism to operate the regulator to cause it to raise or lower said voltage, a pair of secondary relays with their switch members in series relation connected to said mechanism, a pair of primary relays whose switch members control, respectively, the current flow in the coils of the secondary relays, the coils of the secondary relays being energized from a source of energy independent of the supply circuit, each of the coils of said primary relays leading to contacts at one end of a double throw single pole switch whose other end is connected to one of the legs of the supply circuit, means for cyclically operating the double throw switch and a resistor shunting the switch.

3. A voltage regulator system comprising a circuit whose voltage is to be regulated, a pair of lines tapping said circuit, a resistance in one of said lines and a cyclically operated single pole, double contact switch bridging said resistance, one of the contacts of the single pole switch leading to the operating coil of a primary relay, the switch member of said relay being in series with the operating coil of a secondary relay, said secondary relay having a double throw switch, the other of the contacts of the single pole switch leading to the operating coil of a second primary relay, the switch member of said second relay being in series with the operating coil of a second secondary relay, said last relay also having a double throw switch, a reversible motor, leads connecting the double throw switches in series with one another and with the motor in one position of the double throw switches to rotate the motor in one direction on closure of the circuit controlled by said double throw switches, other leads connecting the double throw switches in series with one another and with the motor in another position of the double throw switches to rotate the motor in reverse direction, a voltage regulator connected to. the circuit Whose voltage is to be controlled, and a drive connection between the voltage regulator and the reversible motor.

References Cited in the file of this patent UNITED STATES PATENTS 2,216,599 Minneci Oct. 1, 1940 2,454,107 Wald Nov. 16, 1946 2,571,838 Connor et al Oct. 16, 1951 2,586,076 Nichols Feb. 19, 1952 2,747,157 Pinney May 22, 1956

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