Remote Control Potentiometers Simplify Automation Upgrades

Micronor’s new MR266 series Remote Control Rheostats and MR267 series Remote Control Potentiometers are turn-key solutions for upgrading manual potentiometer-based process controls to automated PLC control. The products offer choice of 4-20mA or 0-10V input/output interface for compatibility with the broadest range of PLC, DCS, A/D, D/A and other control devices. Mounting options include front panel mount (MR267 only) and DIN rail mount. MR266 series replace low power (< 5 Watts) potentiometers in range of 100Ω to 100KΩ. MR266 series replace high power rheostats in range of 2Ω to 50KΩ with four power options (20/60/170/300 Watts).

In addition to analog input/output control, the MR266/MR267 series offer additional features. Three user-adjustable trimpots determine the MIN (4mA/0V input), MAX (20mA/10V input) and SPEED (10-120 seconds) set points. An OVERRIDE mode option allows the system engineer to define how the unit shall respond when a user tries to manually override the unit via the front panel knob. Setting the OVERRIDE DIP switch to ON disables analog input control until a Reset is performed. The optional MR267A OVERRIDE Pushbutton/LED indicator assembly is offered as a turn-key accessory for use with the OVERRIDE mode.

EXAMPLE. A systems engineer wants to automate the speed control of motor drive system which is manually controlled via a 2W potentiometer adjusted within the range of 10-85Ω. The engineer has a PLC interface available with 4-20mA programmable output. The user would specify an MR267 configuration with a non-isolated 4-20mA input and 100Ω potentiometer. Upon receipt of the unit, he would then set MIN (4mA input) corresponding to 10Ω potentiometer setting and MAX (20mA input) corresponding to the 85Ω position. NOTE: The factory default settings are: MIN=0Ω, MAX=100Ω and SPEED=10s.

The MR266 Remote Control Rheostat also offers a convenient way of relocating high power (i.e. hot!) rheostats closer to the controlling equipment - for shorter electrical connections and better thermal control. Simply mount the MR266 unit in the environmentally-conditioned instrument cabinet and then remotely control it from the operator's console via the optional HPFF front panel-mount control accessory.

The MR266/MR267 series remote control rheostats/potentiometers operate from 24V DC with an operating temperature range of -15C/+65C and storage temperature range of -20C/+75C. High wattage rheostats may require temperature derating if operated near their power limits. In small quantities, a typical MR267 motorized potentiometer with non-isolated 4-20mA input is $995 with 2-3 week lead time. The typical MR266 series motorized rheostat configuration ranges from $1295 (20W) to $1495 (60W) to $1695 (170W) to $2495 (300W) - with 4-6 week lead time.