The BFRT250 is a loop powered isolating transmitter that accepts a variety of frequency or pulse input signals. Typical inputs include signals from turbine flow meters, NAMUR proximity sensors, or any device producing a DC pulse or pulsing contact. Frequency range is 5Hz up to 5kHz with an amplitude range of 0.1Vp-p up to 50V pulses. NAMUR proximity sensors are directly connected. Standard output is 4 – 20mA with a minimum supply voltage of 6.3V. This enables the BFRT250 to be used in 12V battery supply systems or in automotive applications. Other factory set output configurations are 10-50mA loop powered and 0-10mA, 0-20mA or voltage output in 3-wire connection up to 40Vdc. Higher voltages are permissible with the use of suitable series zener diodes. Double surge protection is standard with all Series 200 loop powered transmitters to prevent failure due to spikes induced by DC switched inductive loads. The input conditioning of the BFRT250 consists of a charge-pump circuit, converting pulse signals produced by a front trigger circuit to an analogue signal. Final calibration is trimmed using the front accessible zero and span 15-turn trim adjustments. A front mounted L.E.D. and a test socket verify module function and assist in calibration checks without disconnection of output wires.