US2339858A

US2339858A - Arc suppressing means

Info

Publication number: US2339858A
Application number: US448175A
Authority: US
Inventors: Hufnagel Andrew
Original assignee: Union Switch and Signal Inc
Current assignee: Hitachi Rail STS USA Inc
Priority date: 1942-06-23
Filing date: 1942-06-23
Publication date: 1944-01-25
Anticipated expiration: 1961-01-25

Description

Jan. 25, 1944. A. HUFNAGEL ARC SUPPRESSING MEANS Filed June 23, 1942 Jil Patented Jan. 25, 1944 ARC SUPPRESSING MEANS Andrew Hufnagel, Wilkinsburg, Pa., assignor to The Union Switch & Signal Company, Swissvaie, Pa... a corporation of Pennsylvania Application June 23, 1942, Serial No. 448,175

1 Claim.

My invention relates to improved means for reducing the arcing which occurs at a contact which controls the circuit of an inductive winding.

In some types of apparatus a transformer is employed which has a primary winding having an intermediate terminal connected to a source of unidirectional current, while movable contacts cooperate with stationary contacts to alternately connect the other terminal of the source of current to the end terminals of the transformer primary winding.

On interruption of the supply of energy to either portion of the transformer primary winding there is an are between the stationary and movable contacts which erodes these contacts and reduces their life.

It is an object of this invention to provide improved means for reducing the are which occurs between the contacts of apparatus of the type described.

A further object of the invention is to provide means for reducing the voltage induced in each ortion of the primary winding of a transformer on interruption of the supply of energy to this winding portion, and thus reduce the are which occurs at the contacts'which control the supply of energy to this winding portion.

Another object of the invention is to provide improved arc suppressing means.

I shall describe one form of apparatus embodying my invention, and shall then point out the novel features thereof in claim.

In the drawing the single figure is a diagram illustrating one form of apparatus embodying my invention.

In practicing my invention I connect between each end terminal of the transformer primary winding and a terminal of the battery or source of current an asymmetric unit poled to permit flow of energy of the polarity opposite to that supplied from the battery to that portion of the transformer primary winding. These asymmetric units cause each portion of the transformer primary winding to act as a snubbing winding on interruption of the supply of energy to the other portion of the transformer primary winding to thereby retard the collapse of the flux in the transformer core and correspondingly reduce the are caused by the voltage induced in said other portion of the transformer primary winding by the collapse of this flux. 7

Referring to the drawing, there is shown therein a code following relay OR, a transformer T. and a code detecting relay H. Coded energy consisting of energy impulses separated by nonenergy periods is supplied to the relay CR. One terminal of a battery or other source of unidirectional current is connected to an intermediate terminal of the primary winding of transformer T, while when the relay OR is released its contact I 0 connects the other terminal of the battery to the lower end terminal of the transformer primary winding. On the supply of an impulse of energy to the relay CR its contacts pick up and contact In interrupts connection from the battery to the lower end terminal of the transformer primary winding and connects the battery to the upper end terminal of the transformer primary winding. Similarly, on interruption of the supply of energy to the relay CR its contacts release and contact ill interrupts connection from the battery to the upper end terminal of the transformer primary winding and connects the battery to the lower terminal of the transformer primary winding.

When the lower portion of the transformer primary winding is energized flux of one relative polarity is developed in the transformer core, while when the supply of energy to this portion of the transformer primary winding is interrupted this flux collapses. On the supply of energy to the upper portion of the transformer primary winding flux of the other polarity is developed in the transformer core, while any flux remaining in the core from energization of the lower portion of the transformer primary winding is utilized in the energization of relay H.

As a result of changes in the flux in the core of the transformer energy is induced in the secondary winding of the transformer from which it is supplied to the relay H. The energy supplied to the relay H is rectified by contact ll of relay GR in the manner explained in Letters Patent of the United States No. 2,237,788, granted to Frank H. Nicholson and Leslie R. Allison on April 8, 1941.

On movement of the contact ill away from either of its positions with consequent interruption of the supply of energy to a portion of the transformer primary winding the flux in the transformer core collapses and induces a voltage in each portion of the transformer primary winding. The voltage induced in the portion of the winding, the circuit of which has been interrupted, creates an are at the contacts which control the circuit of this winding portion, and this invention provides means to reduce this are.

An asymmetric unit i4 is connected between the upper end terminal of the transformer primary winding and the terminal of the battery which is connected to the movable contact ID. This asymmetric unit is poled to prevent flow of energy through the unit from the battery to the upper portion of the transformer primary winding.

Similarly, an asymmetric unit II is connected/c ing with the result that the flux in the trans former core diminishes and causes a voltage to be induced in both portions of the transformer primary winding. The polarity of the voltage induced in the lower portion of the transformer primary winding is such that current will freely flow through the rectifier l5. Accordingly, the lower portion of the transformer primary winding is short circuited through the asymmetric unit I5 and the battery, and this short circuited winding retards the collapse of the flux in the transformer core with the result that the voltage of the energy impulse induced in the upper portion of the primary winding is much lower than it otherwise would be, while the are which occurs at the contact in the circuit of the upper portion of the transformer primary winding is correspondingly diminished in magnitude.

Similarly, when the contact l0 picks up after it has been in its released position, the supply of energy to the lower portion of the transformer primary winding is interrupted and the flux in the transformer core collapses and a voltage is induced in each portion of the transformer primary winding. The voltage induced in the upper portion of the transformer primary winding is of such polarity that current will flow through the asymmetric unit l4 so the upper portion of the transformer primary winding is short circuited through the asymmetric unit I! and the battery. This short circuited winding delays the collapse of flux in the transformer core and thus reduces the voltage of the energy induced in the lower portion of the transformer primary winding with the result that the are developed at the contact which controls the supply of energy to the lower portion of the transformer primary winding is much smaller than it otherwise would be.

The internal resistance of the battery is relatively low, while the resistance of the asymmetric units to flow of current in the forward direction is also relatively low. Accordingly, the snubbing circuits for the transformer primary winding portions are of low resistance and these windings effectively retard collapse of the flux in the transformer core.

The asymmetric units I 4 and ii are incorporated in the circuits in such manner that they do not interfere with the operation of the equip ment.

On movement of contact I 0 to its picked-up position and the consequent supply of energy to the upper portion of the primary winding-of the transformer. an impulse of voltage is induced in the lower portion of the transformer primary winding. However, this voltage is of the opposite polarity to that induced in this portion of the winding on interruption of the supply of energy to the upper portion of the transformer primary winding and is of the wrong polarity for current to flow through the asymmetric unit It. Accordingly, the lower portion of the transformer primary winding does not function as a short circuited or snubbing winding at this time and does not divert energy from the transformer secondary winding;

Similarly, on movement of contact Hi to its released position to supply energy to the lower portion of the transformer primary winding, an impulse of voltage is induced in the upper portion of this winding, but this voltage is of the wrong polarity for current to flow through the asymmetric unit M.

It will be seen, therefore, that the asymmetric units provided by this invention operate to retard or delay the collapse of the flux in the transformer core on interruption of the supply of energy to either portion of the transformer primary winding, and thus reduce the arcing which occurs at the contacts which control the supply of energy to the transformer primary windings.

Although the invention has been illustrated and described in connection with decoding apparatus of the type employed in railway signaling systems, the invention is not limited to use in this manner but is adapted for use in other situations, as, for example, to reduce the arcing at the contacts of tuned alternators or of B-battery eliminators for use in radio sets.

Although I have herein illustrated and described only one form of apparatus embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claim without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

In combination with an inductive winding having an intermediate terminal connected to one terminal of a source of unidirectional current and having associated therewith alternately closed first and second contacts, said first contact being effective when closed to connect the first end terminal of said winding to the other terminal of said source, said second contact being effective when closed to connect the second end terminal of said winding to the other terminal of said source, are suppressing means comprising a first asymmetric unit connected between the first end terminal of said winding and said other terminal of said source and a second asymmetric unit connected between the second end terminal of said winding and said other terminal of said source, each of said asymmetric units being poled to prevent flow of energy therethrough from the battery to the associated portion of said winding.

ANDREW HUFNAGEL.