Siemens Sitrans Level Measurement, Operation & Application, auxiliary, deactivation hysteresis

Indicator - dynamic Primary Variable (units or % of range)

0-100%		auxiliary
	solid-	power
		pump
current loop connection	state
		power
	output

	Active Shield section	P
	USL
	URV = 100%
solid-	Upper Threshold Setting = %
state	(activation hysteresis)
switch
output
or
2-state	(deactivation hysteresis)
mA output
	Lower Threshold Setting = %
	LRV = 0%
	LSL

3.Upper Threshold Setting and Lower Threshold Setting activate and deactivate the 2-state output, and/or the solid-state output: the settings can be modified to adjust the hysteresis (the window within which the probe is considered ‘covered’).

4.The speed of response to activation and deactivation of the solid-state and/or 2-state output can be modified by Upper and/or Lower Threshold delays.

5.The PV reading can be stabilized if necessary by applying Damping.

6.Overfill or underfill protection can be set in the absence of those conditions by applying the Delta Range Setting.

7.Analog Fault Signalling (menu 08) and Digital Fault Signalling (menu 18) take precedence over the threshold settings (menus 07 and 17).

Level Measurement

The continuous 4-20 or 20-4 mA signal is proportional to the surface level of the product, with an accuracy of 0.1% of the actual measurement (for example, 1mm/m).

Typically, Lower Range Value (LRV - 0%) is set to 4 mA and Upper Range Value (URV - 100%) is set to 20 mA: but the reverse is possible if required. The measurement takes place anywhere within that range. The LCD displays the value as mA, or pF, or percent, depending on the setting for the transmitter variable (TV). If you are using HART, you have the option to define the units.

Operation & Application

7ML19985GE01 SITRANS LC 500 – INSTRUCTION MANUAL Page 13