Dynalco SWT-2000 Speed Switch/Speed Transmitter - Manual (Page 33)

Operating Instructions SWT-2000 DYNALCO
29
7.3.8 Interpretation of System Limit Inputs
Upper and lower set points may be set for each of the 3 system limit inputs. In this way a hysteresis is defined.
If the upper set point is exceeded then this input assumes a status of 1. When the lower set point is then
passed, the status returns to 0. If the actual value lies between the 2 set points then the status is as before.
If a parameters set change takes place when the actual value lies between the set points, the status also
remains as before.
7.4 Fault Behavior
7.4.1 Sensor Error
The sensors may be monitored in 3 ways.
• Sensor powered by the SWT-2000 – Sensor supply current monitoring.
If the current falls outside of the defined range, a static error is signalled.
• Sensor not powered by the SWT-2000 – wire break detection.
Static error is signalled when wire breakage occurs. (Impedance measurement of 2 wire sensor)
• 2 speed sensors connected – Dynamic sensor monitoring, i.e. the 2 signals may be compared. If the
values differ by more than the defined tolerance, dynamic error is signalled.
The SWT-2000 behaviour in the event of a sensor fault is a function of the software configuration. If sensor
monitoring is selected, a fault causes the LED to go off and the analog output (both) go to error status. The
Relay and open collector behavior is a function of the configuration.
7.4.2 System Alarm
The microprocessor continuously monitors the following functions for errors: Supply, math functions of the
micro controller, RAM, EEPROM.
In the event of a fault the relays are de-activated, the current output goes to 2mA (4-20mA) or 21mA
respectively and the Open Collectors become high resistance if assigned to a function other than frequency
output. The SWT-2000 then initializes and attempts to run again.
7.5 Power Failure
If the power fails for longer than the bridging time, the outputs are de-activated, i.e. Analog outputs go to 0mA,
relays de-activate and the Open Collectors go to high resistance.
As soon as the supply returns to the minimum required, the SWT-2000 commences its initialization routine.
7.6 Behavior During Configuration
During the transmission of configuration or process parameters to the tachometer, it goes into a safe mode,
i.e. the outputs assume a defined state. For individual outputs that means:
• Relays: are no longer powered
• Open Collectors: become high resistance
• Analog outputs: assume the fault mode according to the configuration