In this article we will be answering the question, “How do Vacuum Relays Work?” We will be diving into the different types of relay and how relays function.
A vacuum relay consists of two main assemblies: the ceramic “switch” assembly, which contains the high voltage contacts, and the actuator assembly, which holds the actuation coil.
There are two types of vacuum relay. Clapper / Armature type relays and Diaphragm type relays. The Two types of vacuum relays differ in regards to the mechanical actuation.
Clapper / Armature Type
In the clapper type relay, the actuator is located in the vacuum envelope. This traditional design approach provides high mechanical reliability and is adaptable to a number of contact configurations. The contact is actuated by the movement of the spring-loaded armature when the coil is energized. The coil assembly is external to the vacuum package and readily replaceable.
Diaphragm Type
In the diaphragm relay, the actuator is placed outside of the vacuum envelope. This simple, low cost design approach makes use of a thin molybdenum diaphragm which allows contact movement to be transferred into the vacuum package from the external motor assembly. This basic design is used in a large number of vacuum relay products.
The assembly containing the coil is the driving part of the relay and will be connected to the driver circuit. As voltage is applied to the coil, a magnetic field is built up and an electro-magnetic force is created. This force is used to move the mechanism and this the movable contact inside the vacuum envelope. The contact transfers from the N/C to the N/O position in SPDT and DPDT models or, in a SPST relays, opens or closes your high voltage circuit.
Schematic Contact Arrangement / Forms
Vacuum relays come in many different models or “forms”. The different schematic forms are as follows:
SPST-N/O (Form A): Single Pole Single Throw – Normally Open. One operating coil. When the coil is energized the circuit closes.
SPST-N/C (Form B): Single Pole Single Throw – Normally Closed. One operating coil. When the coil is energized the circuit opens.
SPDT (Form C): Single Pole Double Throw. One operating coil. When the coil is NOT energized the circuit is defaults to being in the (NO) normally closed position. When the coil is energized the circuit switches to closing the (NO) normally open position.
DPDT (Form 2C): Double Pole Double Throw. One operating coil. When the coil is NOT energized the circuit defaults to being in the (NO) normally closed position. When the coil is energized the circuit switches to closing the (NO) normally open position.
SPST Latching (Form P): Single Pole Single Throw. Two pulse rated operating coils. These coils are NOT to be continuously energized. Doing so would burn the coils out. When one of the coils is energized the circuit switches to closing the (NC) normally closed position. When the other coil is energized the circuit switches to closing the (NO) normally open position.
SPDT Latching (Form R): Single Pole Double Throw. Two pulse rated operating coils. These coils are NOT to be continuously energized. Doing so would burn the coils out. When one of the coils is energized the circuit switches to closing the (NC) normally closed position. When the other coil is energized the circuit switches to closing the (NO) normally open position.
SPST relays
SPDT relays
DPDT relays
About Max-Gain Systems
Max-Gain Systems, Inc specializes in vacuum relays, vacuum capacitors, insulator products, and other RF components. We offer vacuum capacitors and vacuum relays in Brand NEW, Oldstock NEW, and removed from working equipment tested and guaranteed good. Many customers require NEW, however, we test and rigorously check/test all of our remove from equipment parts. We can offer these at extreme discounts compared to the newly manufactured parts.
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Did you know? We will buy your used and overstock vacuum capacitors and vacuum relays?
Max-Gain Systems, Inc. is the one source to liquidate your excess inventory of vacuum capacitors and vacuum relays. REDUCE warehousing costs, REDUCE aging inventory & OPTIMIZE warehouse space by selling us your unwanted inventory. New and old stock, used and even removed from working equipment, one unit to one thousand plus, you can make money as well as go green. In addition, most of the surplus items we buy are able to go right back into facilities and into the hands of individuals that need a low cost replacement to keep their plants and broadcast stations up and running.
Sell your New and Used Overstock vacuum capacitors and vacuum relays by emailing us. Please include how many, the manufacturer’s part number, and their condition, along with your full contact information. We will reply within one business day.