Test and Measurement

Testing and measurement (T+M) covers a wide range of applications but basically involves detecting a physical variable (current, voltage, temperature, etc.) under various operating conditions (normal, at the operating limits or over-stressed operation) and recording and analysing the result.

Often, measurement isolation from ground is required because the part being tested or measured is, or can be, at a different ground reference voltage from the recording or analysing equipment. When the T+M equipment is line-powered, an AC/DC converter provides isolation and may be followed by a DC/DC converter to provide galvanic isolation between separate power rails for inputs of multi-channel or multi-parameter T+M equipment. This is to avoid cross-talk or interference between the signal inputs. DC/DCs may therefore be necessary even if the measurement unit itself is battery-powered.

Analog input test and measurement sensors commonly require dual rail supplies to power the operational or precision signal amplifiers. The amplified and conditioned output is typically fed into Analog-to-Digital converters and the data stream is then isolated using Digital Isolators. ADCs and DIs require independent 3.3V or 5V rails dropped down from the main 12V or 24V supply rail. Finally, digital bus isolators (USB, CAN, GPIB, etc.) are often essential to avoid ground loops, for safety or to ensure single fault tolerance in the T+M system.

Line powered T+M equipment can range from desktop products to rack installations with input voltage varying from nominal 100VAC to 277VAC, or even higher for some industrial applications. At low power, from 3W to 20W, PCB mounted parts are often used such as the RAC03-K, RAC04-K/277, RAC04NE-K/277, RAC05-K/480, RAC10-K/277, RAC15-K/480, RAC20-K, RAC20NE-K/277, and RAC25-K/480. At higher power, from 40W to 550W, chassis-mounted parts RACM40-K, RACM60-K, RACM90-K, RACM230-G, RACM550-G, and RACM1200-V might be chosen. Fan-less operation is often desirable in T+M environments and all these parts can give useful power to high temperatures without forced air, with the 230W, 550W and 1200W products additionally able to operate with baseplate cooling only. Depending on product, safety certifications are available for different end-application environments, IEC/EN 61010, IEC/EN 62368, IEC/EN 60601, EN 60335 as examples. EMC standards are met without additional components and all parts have low mains leakage current which can be critical in T+M applications, particularly in medical environments. Similarly, for sensitive measurements, the low output noise of the RECOM AC/DC power supplies can be a benefit.

For Test & Measurement equipment in harsh industrial environments such as chemical factories, refineries or power plants, the RACPRO1-Txx series of high power density DIN rail mounting power supplies are ideal. They are specially designed for demanding applications in the industrial sensor and measurement field with a power boost of up to 150% for 5 seconds to handle high inrush currents. The input can be 3AC mains or 450-850VDC. The 240W, 480W or 960W versions all have 24VDC or 48VDC output, which can be safely distributed to lower power multiple sensor systems using the RACPRO1-4SP e-fuse module to individually current limit and protect each output channel.

RECOM offers very high isolation DC/DC converters in compact case sizes. Our exceptional RHV2/RHV3 series offers 20kVDC isolation (12.5kVAC/1 minute) in a SIP16 case for very high isolation power supply measurement technology in applications such as hard vacuum ion pumps, X-ray equipment and high voltage dust filters.

Our REM series offers up to 10kVDC (5kVAC/1 minute) isolation and is certified to withstand continuous 230VAC across the isolation barrier. Output powers from 1W up to 30W are available. An example application is isolation for temperature measurement thermocouples that are attached to transformers, transistors, diodes or capacitors that operate at mains voltages.

For T+M applications that require functional isolation to avoid ground loops or interference in low voltage systems, the RKE series offers exceptional value-for-money with 3kV, 4kV or 6kV isolation options.

An isolated data bus transceiver requires isolated power for the serial communication bus, commonly provided by an isolated DC/DC converter placed across the isolation gap and powered from the input supply. Typical input and output voltage combinations are 3.3V to 3.3V, 5V to 5V or 3.3V to 5V.

Shown below, RECOM can supply a ready-built evaluation board (R-REF03-CAN1) to allow quick prototyping of CAN-bus systems.