for the measurement of electrical variables in heavy current power system RISH Ducer M40 (Fig. 1) is a programmable transducer with a RS 485 bus interface (MODBUS ). It supervises several variables of an electrical power system simultaneously and generates 4 proportional analogue output signals. The RS 485 interface enables the user to determine the number of variables to be supervised (up to the maximum available). The levels of all internal counters that have been configured (max. 4) can also viewed. Provision is made for programming the RISH Ducer M40 via the bus. A standard EIA 485 interface can be used, but there is no dummy load resistor for the bus. The transducers are also equipped with an RS 232 serial interface to which a PC with the corresponding software can be connected for programming or accessing and executing useful ancillary functions. This interface is needed for bus operation to configure the device address, the Baud rate and possibly increasing the telegram waiting time (if the master is too slow) defined in the MODBUS protocol. The usual methods of connection, the types of measured variables, their ratings, the transfer characteristic for each output and the type of internal energy metering are the main parameters that can be programmed. The ancillary functions include a power system check, provision for displaying the measured variably on a PC monitor, the simulation of the outputs for test purposes and a facility for printing nameplates. The transducer fulfils all the essential requirements and regulations concerning electromagnetic compatibility(EMC) and safety (IEC 1010 resp. EN 61 010). It was developed and is manufactured and tested in strict accordance with the quality assurance standard ISO 9001. nSimultaneous measurement of several variables of a heavycurrent power system / Full supervision of an asymmetrically loaded four-wire power system, rated current 1 to 6 A, rated voltage 57 to 400 V (phase to neutral) or 100 to 693 V (phase-ton phase) nFor all heavy-current power system variables n4 analogue outputs nInput voltage up to 693 V (phase-to-phase) nUniversal analogue outputs (programmable) High accuracy: U/I 0.2% and P 0.25% (under reference nconditions) 4 integrated energy meters, storage every each 203 s, storage nfor: 20 years Windows software with password protection for programming, data analysis, power system status simulation, acquisition of nmeter data and making settings DC-,AC-power pack with wide power supply tolerance / nuniversal Provision for either snapping the transducer onto top-hat rails or securing it with screws to a wall or panel