Micronor (www.micronor.com) unveiled its latest turn-key solutions to upgrade manual potentiometer-based process controls for automating programmable logic controller (“PLC”) control, the MR267 series Remote Control Potentiometers and MR266 series Remote Control Rheostats. These products operate at 24 V DC and offer choice of 0-10 V or 4-20 mA output/input interface for compatibility with wide range of D/A, A/D, DCS, PLC and other control devices. Its mounting options include front-panel mount for MR267 only and a DIN rail mount. The MR266 replaces high-powered rheostats ranging from 2.0 to 50 K Ohms with four power options (“20/60/170/300 Watts”).

The MR266/MR267 series has additional features for analog input/output control. Three operator-adjustable trimpots determine the SPEED (“10-120 seconds”), MAX (“20mA/10V input”) and MIN (“4mA/0V input”) set points. Its OVERRIDE mode option permits the system engineer for defining how the unit will respond when an operator tries to override the unit manually through the front panel knob. Setting up the OVERRIDE DIP switch to “ON” disables analog input control until Reset is performed.

For example, a systems engineer wanted to automate the motor drive system’s speed control, which is manually controlled through a 2-W potentiometer adjusted in a range of 10-85 Ohms. The engineer has a PLC interface with 4-20mA programmable output.

The new MR266 Remote Control Rheostat offers a way of moving high-power rheostats near the controlling equipment for better thermal control and shorter electrical connections. Simply mount the MR266 in the instrument cabinet and remotely control it from the user’s console through optional HPFF front panel-mount control accessory.

The new MR266/MR267 remote control rheostats/potentiometers operate from 24 V DC with -15°C/+65°C operating temperature and -20°C/+75°C storage temperature. If used near their power limits, high-wattage rheostats will require temperature derating.