Electricity + Control September 2018

round up

CONTROL SYSTEMS + AUTOMATION + SYSTEMS ENGINEERING

Multi-channel power supplies for absolute accuracy

from the 2230G-30-6. All channels are simultaneously displayed on the front-panel display. To minimise the effects of noise on the device under test (DUT), the triple output power supplies use a linear design with <1mV rms ripple and noise. The linear design also ensures the supplies don’t add to ambient noise and affect other sensitive instrumentation being used for test. Using the supplies’ remote sensing capability, users can set and monitor output voltages with a 0.03% basic ac- curacy and a resolution of 1mV. Load current can be monitored to 0.1% basic accuracy, and 1mA resolution. The programmable multiple output power supplies include both front and rear access to the power outputs for orientation flexibility in test setups, while minimising required lead lengths to reduce noise pickup, minimise losses, and keep the test setup neat. The 2230G Series come with three standard interfaces options for PC-based control: USB, GPIB, and RS-232. Enquiries: Comtest.Tel. +27 (0) 10 595 1821 or email sales@comtest.co.za

Measuring air velocity in HVAC systems The Kobold compact KAH Series airflow velocity trans- mitters, offered by Instrotech, are ideal for accurate ven- tilation control in Building Automation Systems (BAS) and heating, ventilation and air-conditioning (HVAC) applica- tions. They incorporate innovative hot film anemometer technology which guarantees good accuracy at low air- flow velocity and makes the sensor highly reliable and heat resistant.This technology is superior to conventional anemometers with hot wire sensors or NTC bead ther- mistors. The sensor is much more insensitive to dust and dirt than all other anemometer principles, which trans- lates to high reliability and low maintenance costs. The configuration equipment allows air velocity adjustment of the sensor. Apart from measuring air flow velocity, the KAH air flow transducer transmits a normalised signal of 4-20 mA or 0-10 V. The measuring range and the re- sponse time can easily be selected with jumpers as per requirement. Specifications: • Selectable working range: 0 … 10/15 /20 m/s • Output signal: 0 …10VDC or 4 …20mA • Supply voltage 24VAC/DC • Low angular dependence Enquiries: Instrotech.Tel. +27 (0) 10 595 1831 or email sales@instrotech.co.za Comtest, local representative of Keithley, has announced the introduction of the Keithley Series programmable, low-noise, three-channel power supplies that deliver up to 375W in a compact 2U- high, half-rack-wide enclosure. Designed for maximum flexi- bility, accuracy, and low noise when testing LED drivers, automo- tive and power-IC circuits, the power supplies’ three-channels are isolated, independent and individually programmable with remote sensing for each channel. “Designers and test engineers are being challenged to test high-power circuits with a wide range of voltage levels and cur- rent draws in compact test environments, while also ensuring minimum noise and maximum accuracy,” said Lori Kieklak, vice president and general manager, Keithley Product Line at Tektronix. “This is particularly the case in R&D and in stacked, tightly-spaced automated setups with high production throughput. Keithley’s new series of multichannel power supplies provides the best perfor- mance and flexibility needed for testing a wide range of product configurations.” To provide this flexibility, the 2230G-30-3 provides 195W with two 30V, 3A channels and a 5V, 3A channel, while the 2230G-30-6 and 2230G-60-3 provide up to 375W, with two 30V, 6A channels and two 60V, 3A channels, respectively. Both 375W versions also have a 5V, 3A third channel. For higher voltages or currents, 30V channels can be combined in series to get up to 60V, and two or three channels can be connected in parallel to deliver up to 15A

Field controller for dc retrofit applications The new Allen-Bradley PowerFlex DC field controller from Rockwell Au- tomation enables customers to upgrade their dc motor applications to a modern system, without the need for complex external devices. An up-to- date digital networked control system helps customers to gather and lev- erage vital information throughout their enterprises. The dc field controller provides three-phase, four-quadrant (reversing) dc motor or generator field control. The field controller can be used on its own or with a PowerFlex DC digital drive. In stand-alone mode, it provides power to a dc motor field with a fixed reference by using fixed I/O. The field controller can also control electromagnets and other non-motor loads. For dc retrofit applications that require motor reversing, the PowerFlex DC field controller helps eliminate the need for an additional armature bridge or a complex system of external devices, saving customers time and mon- ey. The field controller offers output ratings from 17 A to 575 A and input of 200 V and 500 V. It enhances the capability of the PowerFlex DC drive family, designed for demanding stand-alone and coordinated drive system

applications. The PowerFlex DC drive family is well suited for dc motor applications and retrofits up to 6 000 Hp or 4 000 kW. The PowerFlex DC family has core capabilities aligned with the Pow- erFlex AC family of drives, including seamless integration into a Logix-based environment, flexi- ble feedback and communication options, as well as voltage settings designed to global standards. Enquiries: Michelle Junius. Email mjunius@ra.rockwell.com

10 Electricity + Control

SEPTEMBER 2018