D521-Manual_EN_Rev07 2017_05_26
Page 5 of 31
2.7
Measuring Principle
Measurement is based on the frequency of the pulse sequence representing the speed. Basic
quantity is the time between one or more of its pulses. An automatic function determines this
number, in order to maintain a minimum period of time for every measurement to be extended
over. This time minimum is programmable to 5 milliseconds or more, thus establishing a corres-
ponding averaging and stabilization of measurements.
The corresponding speed value in terms of RPM, by which the display, the alarm circuit, and the
analog output are reading, computes from these measurements. This process further considers
the programmed application data (relation between machine speed and signal frequency).
2.8
Performance at Signal Break
In normal operation, the function closely tracks the input sequence, with the programmed
performance. After a sudden interrupt of the input pulses, the unit reduces the readings following
an automatic step-down sequence. This starts as fast as the most recent measuring sequence
before interrupt but then decreases slower and slower (reciprocal) until it meets the programmed
low end.
2.9
Signal Input V-Path (volts) Terminal 14
Accepting any sensor which meets these conditions:
- High Level path:
Response level on/off : >7/<5 volts DC with programmable hysteresis
Maximum voltage: 100 volts
Input impedance: 100 kOhm
Frequency range: 0 … 50 kHz
Sensor supply: approx. 13 volts / 60 mamps.
- 2-leads NAMUR sensors DIN 19234 (if programmed):
Current level on/off >2.0 mamps / < 1,2 mamps with programmable hysteresis
Sensor supply: 8 volts with 1 kOhm load resistor (incorporated).
Corresponding BRAUN Sensors listed in Wiring Diagrams on page 26.
2.10
Signal Input mV-Path (millivolts) Terminal 15
Accepting low level sensors or such with superposed DC-level, or such missing the above
specified V-levels. Sensitivity (min amplitude required) depending on signal frequency (with
sinusoidal waveform)
500 millivolts RMS between
0.1 Hz
… 1 Hz
50 millivolts RMS between
1 Hz
… 10 kHz
500 millivolts RMS above
10 kHz
Max voltage 50 volts with max ± 35 volts DC superposed.
Input impedance approx. 50 kOhm
2.11
Sensor monitoring
Monitoring sensor current drain, output voltage, and signal activity (if applicable to sensor type).
2.12
Reserved
