FISHER CONTROLS Industrial Partner

Fisher Controls 4211 Electronic Position Transmitter | 0 to 90 degrees of Potentiometer Rotation Simple Type: Electronic Position Transmitter

Fisher 4200 Series electronic position transmitters (figure 1 and 2) combine field-proven electronic and mechanical expertise in a versatile, accurate instrument that senses the position of a device, and sends a standard (4-20 mA) output signal to an indicating device. The instrument is available as a transmitter with integral high and low electronic travel limit alarms, as a transmitter only, or with electronic travel limit alarms only. The instrument can sense the position of rotary or sliding-stem valves, vents, dampers or other devices. When the instrument is mounted, a potentiometer shaft is mechanically connected to the device to sense mechanical motion. For a standard instrument, a single potentiometer is provided for position input or an optional dual element potentiometer is available to allow independent electrical operation of the transmitter and alarm circuits. The instrument has standard, or long-stroke, capabilities for sliding-stem actuator applications. For long-stroke applications, a multi-turn potentiometer attached to a travel transducer assembly is used to sense linear motion of the actuator stem or other devices. The instrument with standard capabilities can also be used on quarter-turn actuators. For instruments equipped with electronic travel limit alarms, individual electronic high and low alarm circuits drive separate high and low alarm SPDT relays. The user adjusts the trip point and deadband of the high and low alarms to the desired travel limits. When the sense potentiometer voltage is higher than the high trip point, the electronic high alarm circuit de-energizes the high alarm relay. When the sense potentiometer voltage is lower than the low trip point, the low alarm circuit de-energizes the low alarm relay. The low trip point may be offset from the high trip point by as little as 5% of the remaining span. In the event of a power loss to the alarm circuits, both alarms are tripped (both relays are de-energized). This indicates a system failure because the actuator cannot be physically at both travel limits simultaneously. The relay contacts are isolated from the transmitter and alarm circuits.