Summary ZTD series intelligence displacer level (interface) transmitters are produced by Dandong Top Electric Instrument Co. Ltd, cooperating with Fisher Controls Company. We import the original FIELDVUE DLC3000 series intelligence level controller, design and manufacture other parts ourselves. ZTD is suitable for level, interface or density measurement with standard output signal 4~20mA DC. Using a Model 275HART Communicator being compatible with DLC3000 series intelligence level controllers, not only can you check, configure, calibrate, or test the intelligent level transmitter, but also, can receive the messages from a single controlling loop and load down the information from field into control system. Principle of Operation ZTD series intelligence displacer level (interface) transmitter consists of imported original FISHER DLC3000 series intelligence level controllers and measuring chamber (cage), measuring mechanism, displacer and torque tube, etc. The liquid level change triggers the change of the displacer’s position. It is transferred into the torque tube unit. This makes the torque tube and core axle rotate synchronously. At the same time, the magnetic steel parts that fixed at the core axle of the torch tube turns an angular shift synchronously with the core axle. The Hall-effect sensor senses the magnet change and converts the magnet signals into current signals. DLC3000 series intelligence level controller measures process variables with a controller and relative electronic circuit, supplies current output, energizes LCD meter parts and supports HART communication. Micro-controller receives the electric signals that have been temperature-compensated and linearised. Meanwhile, compensates the liquid density change aroused by the change of the process temperature. D/A output circuit receives the output from the micro-controller and supplies 4~20mA current output signals. LCD can indicate analog output, process variables, process temperature (if RTD is installed), degrees of the torque tube rotation and percent range of variable, etc.