K-Patents DD-01 - Manual (Page 15)

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5.3. SIGNAL DIFFERENCE ALARM
According to BLRBAC, if a difference of 2% solids (absolute value) or greater exists between refractometer
readings, an alarm shall be activated.
The alarm limit 2% can be changed from the keyboard using the sequence Calibrate/Parameters/Divert con-
trol/Ref. difference limit. If the deviation alarm trips seem too frequent, it may help to increase the signal
damping, Section 5.1.
Note. If the two refractometers have different limit values, the lower value is used by alarm system.
5.4. LOW ALARMS
The low alarm limits are set from the keyboard of the Indicating transmitter. Enter sequence Cali-
brate/Parameters/Divert control. The menu will show “3 Low conc warning limit” and “4 Low conc divert
limit”. The latter has a double function: Both LOW SOLIDS ALARM and DIVERT limit.
The Indicating transmitter display will carry the messages “Solids warning” and “Solids alarm” when the cor-
responding alarms occur.
Note. The alarm limits are set separately for the two refractometers. Each refractometer gives an alarm accord-
ing to its own settings.
5.5. REFRACTOMETER MALFUNCTION ALARM
The built-in intelligent diagnostics of K-Patents Process Refractometer provides a tight control of the opera-
tion. A full test cycle is completed with an interval less than one second. A description of the microprocessor
implemented diagnostics is given below. For details consult the Instruction Manual of the refractometer PR-
01-S. Only errors classified as Equipment malfunctions will cause alarm and removal from the Divert con-
trol system. Process related faults will only cause a message in the Indicating transmitter display. See also
Section 6.3 for additional diagnostics.
The most important test is to check the signal coming from the digital image sensor during measurement. Im-
proper function of light source, optical components, image sensor and sensor driver are recognized by this
test.
The compensation for temperature measurement is checked, both the temperature element and the A/D con-
verter.
The cable between Sensor and Indicating transmitter is checked using a check sum method, thus recognizing
short circuits, open circuits and excessive disturbances.
The microprocessor system has also a self-checking test program to ensure the proper operation of the CPU
and the memories. The constants in the EEPROM memory are tested to be within strict limits of acceptance.
The performance of the microprocessor is of critical importance for the measurement control. A separate
hardware watch-dog circuit ensures the proper microprocessor operation by checking that the microprocessor
regularly sends out a predetermined pulse sequence. Another hardware circuit checks that the supply voltage
to the microprocessor is within safe limits, to prevent any brownout stray output pulses.
5.6. PRISM WASH
A prerequisite for a proper function of the divert system, is that the prism wash works. The TEST value in the
display should increase at least 20 steps during WASH, provided TEST is not close to its maximum value 248.
See Sections 8.1, 8.5 and 9.2 in PR-01-S Instruction Manual.
INSTRUCTION MANUAL FOR DD-01 DOCUMENT/REVISION: IMD 1/5
Effective: June 20, 2005