Different types of relays are used extensively in radio frequency (RF) and high-frequency systems. AMS Technologies provides a comprehensive range of unique RF reed relays to cover most high-frequency applications, whether fast switching RF relays for portable communication systems, or high-power relays for switching high-power RF on and off.
As a worldwide unique product, the reed relays from AMS Technologies are available in many configurations to suit customer needs. Our reed relays utilize a special hermetically vacuum-sealed reed switch that has been optimized for the 3 MHz to 32 MHz frequency range used in RF communications. With voltage isolation of up to 9 kV, a switching capability of up to 50 VA and a carry current of 1.5 A to 20 A at 30 MHz, the RF reed relays can be used as part of an antenna matching unit for manpack communication systems or within a portable system for use on ships or vehicles.
With up to 15 kV of isolation at 3 A of current, our broad range of high-voltage (HV) reed relays are very compact and efficient devices – even the smaller‘S’ sized packages can provide 5 to 7 kV of isolation. Reed relays are often used in HV test systems, ATE, cable testers and medical defibrillators, amongst others.
Vacuum relays are electro-mechanical relays optimised for use where high voltage needs to be switched on and off at high frequency. They commonly form the main switching element in medical MRI scanners, vapour etch deposition systems and RF broadcast transmitters, where SPST and also SPDT relays for up to 33 kV are available. With a maximum carry current of 110 A, these relays are also fully ›Mil Spec‹ rated.
AMS Technologies supplies both vacuum and gas filled relays to cover the full spectrum of high-voltage applications. With isolation voltage from 10 to 70 kV for currents of up to 70 A, these relays are a good solution where size, weight and electrical safety are of importance. Typical applications may include capacitor discharge in defibrillators or high power isolation in portable communication systems. With excellent relationships with suppliers using vacuum or gases in differing switching technologies, AMS Technologies can provide its customers with a compact switching device suitable for high voltages and currents. Get in touch with the AMS Technologies high voltage experts to discuss your customized solution.
In many utility and safety applications, hermetically sealed vacuum switches are required in explosive as well as normal environments. The contactors available from AMS fulfil all these requirements and provide a cost-effective solution for all DC and AC switching applications where high voltage and high power need to be controlled. Our small and lightweight DC contactors’ rugged design with high voltage and current ratings allows for endless applications. And within our range of three-phase vacuum contactors you find devices for switching currents of up to 200 A RMS at voltages up to 0.6 kV, as well as contactors capable of switching up to 450 A RMS at up to 1.5 kV or even up to 7.2 kV respectively.
Complementing our portfolio of high-voltage and radio frequency relays and contactors, AMS Technologies carries high-voltage power supplies, HV pulse generators, high-voltage power modules including HV AC/DC converters, capacitor chargers, and HV DC/DC converters.
Whether high voltage, pulse discharge, RF, filtering, precision or wound film capacitors, AMS Technologies has the expertise and capacitors product range to meet your requirements. Our broad capacitor product portfolio ranges from ceramic capacitors for HF and high voltage operation and filter or snubber capacitors with polypropylene dielectrics to specialty vacuum/gas capacitors for high energy storage and pulse discharge all the way to capacitors for RF use or water-cooled devices rated to 4,000 kVA.
In addition to capacitors, AMS Technologies carries a broad range of further passive components, including a large portfolio of resistors, featuring special resistor technologies with extremely low inductance, rated for especially high power (up to 100 kW), high voltage (up to 48 kV) or high temperatures (up to +275°C), variants for RF applications, but also components featuring extreme long-term stability (up to 0.025% per 1,000 hours in extended load life) or ultra-low temperature coefficients (as low as 2 ppm/°C). Packages range from small surface-mount versions all the way to 1-m-long water-cooled, high- load resistors with 10 cm in diameter.
Mechanical relays and contactors are electromagnetic switching devices, usually working according to the electromagnet principle. A current in the excitation coil, which is connected to the control contacts of the component, generates a magnetic flux through the ferromagnetic core and a movable armature, which is also ferromagnetic. At an air gap, force is applied to the armature, causing it to switch one or more operating contacts. The armature is returned to its original position by its inherent spring force as soon as the coil is no longer energized.
Control and operating contacts are almost always galvanically separated from each other. Thus, a low voltage and a low current through the excitation coil can reliably, safely and reproducibly switch a much higher voltage, a significantly higher current or even a high-frequency signal at the operating contacts.
Relays and contactors differ primarily in the amount of current through the operating contacts that they can switch. As a rough guide, relays switch currents up to about 10 A, while contactors are suitable for switching currents above 10 A – with spring-loaded operating contacts to ensure the circuit is broken when facing an overload condition, avoiding the contacts to be welded together. Contactors are available as single-phase as well as three-phase models for controlling large electric drives.
Relays are mostly used for closing and opening DC and AC control circuits and can perform control functions as well as protection and signal conversion functions. The input parameter of a relay is usually an electrical variable such as voltage or current, and the output parameter is a change in the output circuit or electrical signal.
The function of the operating contact(s) of a relay can be either "normally open" (NO) or "normally closed" (NC). This specification always refers to the idle state of the relay, i.e. when no voltage is applied to the control contacts or no current flows through them. This means that NC type operating contacts are electrically conductive when no voltage is applied to the relay's control contacts. In contrast, the operating contacts of contactors are always "normally open", i.e. current only flows through them when the control coil is energized.
In addition to single operating contacts (normally closed, normally open, changeover), relays can also have several pairs of contacts. Typical configurations here are SPST (Single Pole, Single Throw), SPDT (Single Pole, Double Throw), DPST (Double Pole, Single Throw), DPDT (Double Pole, Double Throw). “Pole" indicates the number of circuits the relay controls, while "Throw" defines the number of active possible end positions of the actuator: ST relays close a circuit in only one position (the other position is "off"), while DT relays close a circuit in both possible positions.
Reed relays utilize two reed switch blades of a ferrous nickel construction and encapsulate them in an evacuated glass capsule, thus allowing for the remote control, via a coil which generates a magnetic field to close or open the reed switch.
Radio frequency (RF) reed relays are designed to switch AC signals with a high frequency (e.g. 30 MHz), using appropriate contact material like Rhodium and sometimes fully screened coils for low RF loss. High-voltage (HV) reed relays are specifically designed for high-voltage applications, e.g. up to 15 kV DC. Both types of reed relays are available with a broad range of connecting electrodes, ranging from through-hole PCB mount contacts to turret or spade contacts, silver-plated contacts for ultra-low RF losses, to flying lead connections.
Using vacuum as the dielectric in relays and contactors is a very effective way to inhibit breakdowns across the contacts. While in vacuum relays, vacuum is generally used as the best dielectric for isolation of high voltages, gas filled relays are preferred to cope with the effects of capacitive discharges due to their arc-quenching capabilities.
Alternative Terms: Reed Relay; Vacuum Relay; Gas-filled Relay; High-voltage Relay; HV Relay; HV Reed Relay; Radio-frequency Relay; RF Relay; RF Reed Relay; Three-Phase Contactor; Vacuum Contactor