Honeywell 621-3502 PLC Module

Honeywell 621-3502 PLC Module

Brand: Honeywell

Module: 621-3502

Description: PLC Module

Product Orgin: USA

Honeywell 621-3502 PLC Module. Positive migration fault: When judging the measurement accuracy of the differential pressure transmitter in the positive migration state, the following two problems will be encountered: One is the instrument output error, if the installation of the normal order of operation, should first close the differential pressure transmitter three valve group of positive and negative pressure measurement, and then balance valve open and empty the instrument plug operation, 4mA limit value should be much higher than the instrument output value, if the instrument output value is greater than the limit value, then it indicates that the operating device there is a blockage phenomenon, The most likely location of failure is the three-valve group and the positive pressure chamber lead; Second, the migration or zero display is not normal, if the pressure point of the positive pressure chamber and the vent switch are closed and opened in turn, the instrument output should be displayed in the normal case of 4mA, then in the migration or zero are small, the instrument output value will be significantly lower than 4mA, on the contrary, if the instrument output value is greater than 4mA, At this time, the zero or migration amount will also increase, in addition, the spacer leakage or not filled will lead to the occurrence of spacer infiltration in the positive and negative pressure chamber.