Emerson 4000 manual Recommended Configuration, MA Signal Upon Critical Alarm, Calibration

Oxymitter 4000

Instruction Manual

IB-106-340 Rev. 3.0 December 2003

3-3 RECOMMENDED CONFIGURATION

a.4-20 mA Signal Upon Critical Alarm

Rosemount recommends that the factory default be utilized. The 4-20 mA signal will go to the 3.5 mA level upon any critical alarm which will cause the O2 reading to be unusable. Customer can also select 21.6 mA as the failure setting if normal operations cause O2 readings to go below the zero % O2 (4 mA) level.

If the O2 measurement is being utilized as part of an automatic control loop, the loop should be placed into manual upon this failure event or other appropriate action should be taken.

b.Calibration

Rosemount recommends utilizing an autocalibration system, actuated by the “calibration recommended” diagnostic. New O2 cells may operate for more than a year, but older cells may require recali- bration every few weeks as they near the end of their life. This strategy ensures that the O2 reading is always accurate, and eliminates many unnecessary cali- brations based on calendar days or weeks since previous calibration. When utilizing the SPS 4000 or the IMPS 4000, consider wiring some or all associated alarm contacts.

1.CALIBRATION INITIATE. Contact from the control room to an SPS 4000 or IMPS 4000 (one per probe) provides the ability to manually initi- ate a calibration at any time from the control room. Note that calibrations

can also be initiated from a HART handheld communicator, from Asset Management Solutions software, or from the keypad on the Oxymitter 4000.

2.IN CALIBRATION. One contact per probe provides notification to the control room that the “calibration recommended” diagnostic has initi- ated an automatic calibration through the SPS 4000 or IMPS 4000. If the O2 signal is being utilized in an automatic control loop, this contact should be utilized to place the control loop into manual during calibration.

3.CALIBRATION FAILED. One con- tact per probe from an SPS 4000 or IMPS 4000 to the control room for notification that the calibration pro- cedure failed. Grouped with this alarm is an output from a pressure switch which indicates when the cali- bration gas bottles are empty.

4.4-20 mA SIGNAL DURING CALI- BRATION. The 4-20 mA signal can be configured to respond normally during any calibration, or can be con- figured to hold the last O2 value upon the initiation of calibration. Factory default is for the 4-20 mA signal to operate normally throughout calibra- tion. Holding the last O2 value may be useful if several probes are being av- eraged for the purpose of automatic control. Unless several probes are being averaged, always place any control loops using the O2 signal into manual prior to calibrating.

Rosemount Analytical Inc. A Division of Emerson Process Management Configuration with Keypad 3-5