BG80 USE AND MAINTENANCE BOOKLET
Rev.1 of 23/04/2013 of BG80 uk agg2013 Page 19 of 40
If the number of motor revolutions is too low when an inverter is used, strong vibrations and lateral
oscillations may occur; in this case the number of revolutions should be increased to avoid damage to
the mixer and to the tank
If satisfactory mixing performance is not achieved despite having observed the above-listed instructions, (as a
result of the large diameter of the tank or the high proportion of dry content), the mixer dealer or manufacturer
should be promptly informed.
The dealer or the manufacturer shall not be held responsible for damage resulting from incorrect use of the
mixer.
Potential formation of floating material on the surface may be due to:
- Digester tank filling with an already fermented substrate from other tanks of the Biogas plant:
- A high proportion of dry material content;
- A fault in the Biogas system and consequent unexpected mixer run-down time;
- A fault in the mixer.
If large quantities of floating material are present, the necessary counter-measures should be taken
before starting the mixer. These measures must be agreed upon with the dealer or manufacturer of the
mixer.
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5
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4
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OPERATION WITH INVERTER
To enable inverter-powered operations, the motors are equipped with a temperature control system using PTC
or PT 100 thermistors inserted in the coil that ensure that the temperature range limits are maintained.
The user must connect the terminals of the PRC or PT 100 to a trip relay that will cause the electrical
supply to disconnect if dangerous temperatures are reached.
This trip system must only ever be reset manually, never automatically.
In order to comply with regulations the user must:
- Use a trip system that complies with the principles of standard IEC 61508 (must be Fail Safe);
- Use a double protection circuit.
The motors for inverters are equipped with a supplementary plate. Before starting the motor, check that it
meets the performance requirements (kW, Hz and torque) indicated on the supplementary plate; in the absence
of these indications, the user should contact the manufacturer.
If powered by an inverter, the power may be slightly reduced to maintain the specified temperature range and
prevent potential damage from overheating.
When choosing an inverter, the user must consider that the motor must not be subjected to voltage peaks
greater than 1.4 times the nominal voltage; otherwise, the lifespan of the coil insulation will be slightly reduced.
It should be borne in mind that if an inverter is used, the installer is responsible for carrying out the checks and
taking any necessary precautions in relation to emission and immunity limits as per the "Electromagnetic
Compatibility (EMC)" directive 2004/108/EC and subsequent modifications.
