Clacton-on-Sea, England. Pickering Electronics announced it will be showcasing its latest high-voltage reed relays at the Teradyne Users Group vendor fair on May 2, 2017, in San Francisco.
Pickering Electronics said it has expanded its high-voltage single-in-line (SIL/SIP) reed relay range to include three new series that all offer higher packing density: the Series 67 and 68 dry reed-relay range for up to 10 kV and the Series 119 micro-SIL range for up to 3 kV.
The company calls the Series 119 the industry’s smallest high-voltage SIL/SIP reed relay for up to 3 kV stand-off: the 1 Form A, 2 Form A, and 1 Form B versions are available with either 3-, 5-, or 12-V operating coils. The 1 Form A, 1-kV version has four pins on 0.15-inch (3.8-mm) pitch, the same as the long-established Series 109P. These can be stacked side-by-side for maximum packing density (all Pickering SIL/SIP relays have full magnetic screening allowing side by side operation).
This Series 119 relay is intended for voltages considerably higher than standard small SIL/SIP relays, suitable for cable and backplane testers and mixed-signal ATE. Pickering also offers other SIL/SIP high-voltage dry reed relays with the Series 104 for use up to 3-kV stand-off, 25-W switching.
The Series 67 and 68 reed-relay range are available for up to 10-kV stand-off, 7.5-kV switching, with an option of either PCB or flying-lead switch connections. Similar in specification to the long-established Series 60/65, these new relays are manufactured in a SIL/SIP format using former-less coils, which dispense with the more usual coil-supporting bobbin, allowing a smaller package than similar rated devices.
The unusual package design does present some interesting packing possibilities for high density applications such as multiplexers and matrices in instrumentation and test systems. 5-, 12-, and 24-V coils are available as standard, and other voltages can be supplied to special order, as can variations in the lead length of the Series 68 range. The relays are suitable for high-voltage transformer and cable test and some electro-medical applications such as defibrillators.
The long-established Series 60, 62, 63, and 65 are suitable for up to 15-kV stand-off, 12.5-kV switching at 50 W maximum. The Series 62 and 63 also come with push-on connections on the top face. Like the Series 67 and 68, these larger parts all feature robust tungsten plated contacts to ensure a long and reliable life.
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Reed Relays generally have a higher Carry Current rating than their ‘hot’ Switching Current rating. It is usually during ‘hot’ switching where contact damage occurs due to the resulting arc across the contacts as they open or close.
A severe current overload will quickly melt the contact area causing the two surfaces to fuse together creating a hard weld as soon as the contact closes. Less severe current inrushes will cause a milder weld or gradually build up a ‘pip’ on one contact and erode a ‘crater’ on the other according to the direction of current flow. These can eventually lock together. Arcs can occur when contacts open, particularly when the load is inductive and Back EMFs from inductive loads should always be limited, usually by a simple diode in the case of DC loads or by a Snubber or Varistor in the case of AC loads.
One way to reduce or remove these issues is to ‘Cold’ switch. This is a common technique in Test Instrumentation, where the current or voltage stimulus is not applied to the switch until after the relay has been operated and contact bounce finished. In the same way, the stimulus is removed before the contact is opened. In this way, there will be no arcing or switched current inrushes and the relay will achieve maximum life, often into billions of operations.
When calculating the delay time between switching on the relay coil and applying the current to the switch, it is important to consider the effects of high ambient temperature if this is likely to be encountered. The maximum operate time and bounce figures given on the data sheets are at a 25°C ambient level. At higher temperatures, the resistance of the coil winding will increase at a rate of 0.4 % per °C, this being the coefficient of resistance of the copper coil wire. There will therefore be a corresponding fall in coil current and the level of the magnetic field that is generated to operate the reed switch. This lower drive level will increase the operate time slightly.
The timing figures on Pickering data sheets are normally quite conservative so this is unlikely to be an issue up to the normal ambient specification of 85°C. However, if there is any additional self-heating within the relay due to a high carry current and the switch resistance (I²R Watts), it will be necessary to consider this and allow a little more time before turning on the current through the switch.
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Pickering Electronics will be showcasing its latest high density range, including the addition of two pole reed relays to their established Series 115, at Semicon Korea on 8 – 10, February 2017 on stand 2811.
The newly released Series 115, 2 Form A relays can switch up to 15 Watts, 1 Amp and require a board area of only 0.15 x 0.4 inches (4mm x 10mm), an increase of only 50% over the single pole version. These relays are the ideal choice for high density two pole matrices and multiplexers.
Two switch types are available. Both types have sputtered ruthenium contacts for long life and high reliability. Switch type number 1 is better suited for general purpose applications. It has a layer of copper beneath the ruthenium to help dissipate the heat from the contact area. This gives an improved current inrush handling ability. Switch type number 2 should be chosen for low level or ‘cold’ switching applications.
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Pickering Electronics, a leading provider of Reed Relays, will be showcasing its latest high density range at the International Test Conference on booth 216, 15 – 17 November 2016.
The Pickering Series 115, Series 116 and Series 117 are three ranges of small Single Pole (1 Form A) reed relays ideal for the construction of high density matrices or multiplexers. These three ranges have identical pin configurations allowing a common PCB for all types but allowing the designer a range of switch ratings according to which part is fitted. The reed switches are vertical within the package which permits a common footprint with a board area of only 3.8mm x 6.6mm. Only the profile height changes with the increasing power or current ratings.
The Series 117 has a height of 9.5mm and is rated at 0.5 Amps switching at 5 Watts. The Series 116 has a height of 12.5mm and is rated at 0.5 Amps switching at 10 Watts. The Series 115 has a height of 15.5mm and is rated up to an impressive 1.0 Amp switching at 20 Watts. Double pole (2 Form A) versions are also available in the Series 116 and 117.
One benefit of the very small size of these relays is that it often makes it possible to increase the functionality of existing designs without increasing the size of the printed circuit boards.
All feature instrumentation grade reed switches with sputtered ruthenium contacts, making them an ideal choice for low level or ‘cold’ switching applications.
They have the option of an internal diode across the coil connections for Back EMF suppression and feature Pickering unique SoftCenter® construction as well as an internal mu-metal magnetic screen. Mu-metal has the advantage of a high permeability and low magnetic remanence and eliminates problems that would otherwise occur due to magnetic interaction. Relays of this size without magnetic screening would be totally unsuitable for applications where dense packing is required.
To learn more visit Pickering on booth 216 at ITC this November, or contact Pickering today to request your free sample board of Pickering ultra-high density Reed Relays visit the website.