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Knowledge Base Articles»KB100001 - How to activate an …
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Last modified on 12/5/2018 4:39 PM by User.


KB100001 - How to activate an "Equipment Off-line" status?

For Rankine Cycle Plants

The first data point in the system must be an acquired point for gross generation.  If this point goes into quality alarm, all the calculated points in that unit will return a value of zero (0) with an Equipment Off-line alarm status (points display with black background and gray text). All the other acquired points will continue to update normally.

In addition, if you set the minimum load for the unit in Low-Low Operational Alarm limits on the gross generation Point Configuration form, all the EtaPRO calculations will “turn off”. In this case, the entire EtaPRO system is set to the Equipment Off-line alarmstatus. 

If EtaPRO cannot acquire a good quality value for gross generation or gross generation is below the unit’s minimum load, there is no point in carrying out the performance calculations. The unit is either in startup or shutdown, or there is some issue with the historian, DCS, or instrumentation that is preventing EtaPRO from acquiring a good quality gross generation signal. Since so many calculations depend on gross generation, there is no point in carrying out the performance calculations if the gross generation input is bad. In addition, if the unit is in the midst of a startup or shutdown, most of the performance calculations will have little value because the unit is outside its normal operating range and/or the load is changing rapidly.

For Combined Cycle Plants

There may not be one acquired point in a combined cycle unit that has as large an impact on calculations like gross generation in a Rankine cycle plant. In addition, the plant may be capable of running in different modes (2x2, 1x1, simple cycle, etc.), in which case you would not want to turn off all the calculations at once. Typically for these plants, individual combustion and steam turbine data points are turned off rather than the whole system. To defeat the feature in the code that uses the first data point in the system to turn off all performance calculations, the first data point is configured so that it can never have bad quality. Typically this point is NULL, a point which always has a value of zero (0) and good quality. This data point should always be the first point in the system and should not be moved. The next section provides the formula for setting individual pieces of equipment to the off-line status

For Specific Equipment

For either Rankine cycle or combined cycle units, individual pieces of equipment are turned off using the Offline function in a user-defined formula data point type. The format of the function is:  Offline(variable, low limit, high limit) If the value of the independent variable falls outside the low or high limits, the function returns an Equipment Off-line operational alarm.

The independent variable(s) is typically something which indicates that the piece of equipment is running (GT output, running status; ST output; pump flow, speed, or motor amps, etc.). This Equipment Off-line alarm status is then propagated to any point that uses this independent variable as an argument. In this manner, EtaPRO can turn off all the calculations for a specific piece of equipment.

Some examples are shown below:

For additional assistance with this procedure or to report an error, please contact EtaPRO Support at or 716-799-1077.