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12.2
Stirring bar breakaway monitoring
When the unit is switched on, the stirring bar breakaway monito-
ring function is displayed (On/OFF SAFE rpm).
Stirring bar breakaway can occur with any magnetic stirrer.
Breakaway can occur when stirring at high speeds or when large
stirring bars are being driven at speeds close to the magnetically
transmissible maximum torque and there are variations in medium
viscosity or controller fluctuations.
On the RET control / t you can select the stirring bar breakaway
monitoring function which operates in the setpoint speed range
between 300 and 1200 rpm.
When stirring bar breakaway is detected, stirring is stopped
momentarily to enable the stirring bar to be picked up. After this,
stirring starts again and ramps up to the setpoint speed (< flas-
hes). If a further stirring bar breakaway occurs within the next 3
minutes of stirring at a constant setpoint speed, the stirring bar
will be picked up again and stirring will restart but this time at the
setpoint speed reduced by 100 rpm. The red LED "Temp" flashes
and the buzzer will sound for several seconds. After the fourth stir-
ring bar breakaway – with less than 3 minutes normal stirring – the
error message ER 41 will be displayed (the motor will continue to
run and the heating is switched off) the red LED "Temp" will flash
and the buzzer will sound. When further stirring bar breakaways
occur, the speed will be reduced each time in 100 rpm steps until
the minimum of 200 rpm is reached. The speed is no longer dis-
played. In this case you should select new test conditions.
IMPORTANT: You must calibrate and test the stirring bar
breakaway monitoring function for your particular configura-
tion taking into account the stirring bars, speed, vessel and
medium you are using.
The reliability of stirring bar breakaway monitoring increases as the
transmitted torque increases.
In a glass beaker filled with water, the function will detect the
breakaway of stirring bars longer than 50 mm (d=8 mm) in the
speed range from 300 to 1200 rpm. Increasing the stirring bar
length, the stirring bar surface area (e.g. TRIKA coated bars) or
increasing the speed will increase the torque transmitted.
022009
The stirring bar breakaway monitoring function will not ope-
rate if the stirring bar breaks away while the stirring is still
ramping up to the setpoint speed.
12.3
Setting the intermittent mode and the stir-
ring bar breakaway monitoring function
• Switch off the unit at the main switch ON/OFF.
• Hold the foil keys "Mot" and "Mode" pressed down and switch
on the main switch ON/OFF. After approx. 5 seconds release the
foil keys.
• After the display self-test (when all the LCD segments flash), the
message On or OFF IntErmit will be displayed.
• Press the foil key "Mot" within the next 5 seconds to switch the
intermittent mode ON or OFF as required.
• If you disable the intermittent mode by selecting OFF, the mes-
sage On or OFF Safe rpm will be displayed.
• To switch the stirring bar monitoring function ON or OFF, press
the foil key "Mot" within the next five seconds.
IMPORTANT: These changes will be stored to memory when the
self-test (SAFE H or SAFE P OK is displayed) has been completed.
13
Timer
Set the function "Heating" by the timer.
• Switching on the timer
Activate the timer by pressing the "Timer" membrane key; the
"SV" symbol will flash.
• Setting the timer
Set the desired time (0:00 - 9:59 h) by turning the left knob minu-
te by minute.
Caution! When the time is set to 0:00 the timer function is swit-
ched off!
• Starting the timer
Start the timer by switching on the "Heating" function; the "
symbol will flash.
"
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