Burkert Type 8025 - Manual (Page 27)

27
Wiring
Type 8025 / 8035
8. WirinG
danger
risk of injury due to electrical voltage.
• Shut down the electrical power source of all the conductors and isolate it before carrying out work on the system.
• Observe all applicable accident protection and safety regulations for electrical equipment.
Insert the supplied stopper gaskets into the unused cable glands of a wall-mounted or a compact version to ensure
the tightness of the device.
Only move the selectors when the power supply is off.
• Use a filtered and regulated 12-36 V DC power supply. The circuit has to be safety extra low voltage (SELV), with a
safe energy level.
• Make sure the installation is equipotential. See chap. "8.1".
• Use shielded cables with an operating temperature limit of 80 °C minimum.
• Do not install the cables near high voltage or high frequency cables; if a combined installation cannot be avoided, a
minimum space of 30 cm should be respected.
• Protect the power supply by means of a 300 mA fuse and a switch.
• Protect the relays by means of a max. 3 A fuse and a circuit breaker (depending on the process).
• Do not apply both a dangerous voltage and a safety extra-low voltage to the relays.
8.1. making the installation equipotential
To ensure the equipotentiality of the installation (power supply - device - fluid):
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Connect together the various earth spots in the installation to eliminate the potential differences that may occur between
different earthes.
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Observe faultless earthing of the shield of the power supply cable, at both ends.
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Connect the negative power supply terminal to the earth to suppress the effects of common mode currents. If this con-
nection cannot be made directly, a 100 nF/50 V capacitor can be fitted between the negative power supply terminal and
the earth.
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Special attention has to be paid if the device is installed on plastic pipes because there is no direct earthing possible.
Proper earthing is performed by earthing together the metallic instruments such as pumps or valves, that are as close as
possible to the device. If no such instrument is near the device, insert metallic earth rings inside the plastic pipes upstream
and downstream the device and connect these parts to the same earth. The earth rings must be in contact with the fluid.
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