KROHNE BM 500 EN - Manual (Page 16)

5
OPERATION
16
BM 500
www.krohne.com 12/2013 - 4003176301 - MA BM 500 R02 en
5.1 Start-up
Before connecting to power, please check that the system has been correctly installed.
This includes:
• The device must be mechanically safe and mounted in compliance with the regulations.
• Check that the measuring rod is not in contact with the vessel wall.
• Check the leak-tightness at the leakage inspection hole of the sleeve or adaptor.
• Make sure that the M12 plug is properly connected or the M16 cable gland properly tightened.
• The power connections must have been made in compliance with the regulations.
• Check that the electrical operating data of the power supply are correct.
5.2 4 and 20 mA setting
• The green LED indicates that supply voltage (> 18 V) is present (operation indicator).
• The 2 red LEDs show different flashing rates (LED monitor), according to the control of the
current output.
• The level meter can be installed at the top or the bottom of the tank.
• The level meter is factory calibrated for installation from the top. This corresponds to 4 mA at
the lower rod end and 20 mA at the upper end (lower part of the conical section of the
measuring rod; see drawing on page 11). When installed from the bottom, the current will
drop down step by step until the tank is empty or the current hits 2.4 mA.
• 4 and 20 mA setting: 4 and 20 mA setting: 4 and 20 mA setting: 4 and 20 mA setting:
This procedure is only required when a smaller measuring range is needed than the
maximum measuring range calibrated from factory or in case of a big difference in
conductivity with tap water exits. When two liquids are present - choose the liquid with the
lowest conductivity for the lowest level setting.
1. Bring level to 0% level - then press for > 3 seconds the 4 mA setpoint key. The 4 mA red
LED is "ON" which confirms the setting.
2. Raise level to 100% level - then press for > 3 seconds the 20 mA setpoint key. The 20 mA
red LED is "ON" which confirms the setting.
• In bottom mounting position: In bottom mounting position: In bottom mounting position: In bottom mounting position: The level meter will show a negative value, when the level
representing the 20 mA level, accidently was set at a lower level than the 4 mA level.
• Resetting to factory calibration: Resetting to factory calibration: Resetting to factory calibration: Resetting to factory calibration:
Press simultanously for > 3 seconds both setpoint keys, both red LEDs will continously flash
to indicate that the level meter is reset. Repeat above calibration procedure for setting the 0%
and 100% values.
• The "dry" signalling threshold is set simultaneously with the low level calibration. When the
conductivity measured here is undershot, the sensor signals the "dry" condition with a
current output value of 2.4 mA. Given different products with widely differing conductivity, the
4 mA adjustment should be carried out using the least conductive liquid.