Instructions for calculating performance indicators

 

POWER PLANT

Instructions for calculating performance indicators

Content:

This report contains a description of the guidelines for calculating the indicators of generation units and methods of data collection, and includes the following parts:

1- Definitions

2- Calculations of exit time and low capacity.

3- Performance indicators and equations.

report

1- Definitions:

      1-1 Outages:

1-1-1 Shutdown occurs when the unit is offline (out of service) and not in the Reserve Shutdown state.

1-1-2 The exit calculation begins when the unit’s connection to the network fails, or when its status changes from a certain status to the out-of-service status, and ends when it is connected to the network or when its status changes to another status “according to the permissible conversion of the units facts Table No. (1) ".

1-1-3 In the case of converting from one exit type to one of the other types, the real (actual) time is accurately monitored where the start time of the next exit type is the end time of the previous exit. When overlaps some times between two types of exit, such as the emergency-exit (U1) and the planned exit, the planned exit period (PO) is not calculated until the problem that forced the unit was removed and the unit is able to return to service although the maintenance can directly work on the planned exit.

It was agreed that the calculation of the planned exit period (PO) would be started on time only in the event of a forced-sudden exit (U1), less than a day before its start.

1-1-4 exit types:

 They are classified into seven types as follows:

PO planned exit

Planned Outage

It is a pre-planned exit for a standard/specified period of time. This exit is planned before starting its implementation with a sufficient period of time estimated at several weeks, and it occurs once or twice a year.

It was agreed that the planned exit (PO) would be the exit for periodic maintenance of all kinds (light maintenance, medium maintenance, comprehensive overhaul, repair work, and permanent modifications, usually included in the annual maintenance program).

).

MO out for maintenance

Maintenance Outage

It is the exit for maintenance that can be postponed to the following week and requires the unit to be taken out of service or to be transferred from any other exit or from its ready-to-operate position. It must be implemented before the next planned exit (PO). The maintenance exit is done at any time of the year and is characterized by flexibility in the starting time and there is no standard/specific time for its implementation period, and it is usually the shortest period of the planned exit.

SE Extension Programmed Exit

Extension Scheduled Outage

An extension of the planned exit (PO) or maintenance exit (MO) beyond their expected period of time.

Extension for programmed exit occurs when the main work scope requires additional time to finish. The rollover time for programmed exit cannot be calculated when the scope of work changes, whether due to the presence or occurrence of unforeseen problems, but rather it is recorded as forced exit (U1).

Extension of Scheduled Exit (SE) as well as Forced Exit (U1), must be precisely logged (month, day, hour, and minute) after the Planned Exit (PO) or Maintenance Exit (MO) has ended.

SF failed to start

Startup Failure

It is the exit as a result of the unit being unable to enter the network within a certain time to start up and it comes after the unit is out or in the state of readiness for operation. Another case "according to Table No. (2)".

You must remember that:

Definition of the Startup Period: It varies from one type to another type of station, as it depends on the state of each unit alone at startup (hot mode, cold mode, ready-to-run state, .... etc.). The start-up period starts from the moment the automated command is given to operate the unit and ends with its connection to the network.]

U1 Unplanned Exit (Forced) - Sudden

Unplanned (Forced) Outage-Immediate

It is the exit that requires the unit to be taken out of service immediately, or from another state of exit or from the state of being ready for operation. This type of exit is usually the result of a mechanical, electrical or control failure, which causes the operator to take it out based on the warning (if you do not exit with the protection systems).

It was agreed that it is the exit that requires the unit to be removed from service immediately, or from one of the cases

 (PO, MO, SE, SF, U2, U3, RS).

U2 Unplanned Exit (Forced) - Late

Unplanned (Forced) Outage-Delayed

It is the exit that requires the unit to be taken out of service sooner but within 6 hours, and this type of exit is only when the unit is in service.

It was agreed to be the exit that would require the unit to be taken out before the next peak period rather than being restricted to a period of (6) hours.

U3 Unplanned Exit (Forced) - Delayed

Unplanned (Forced) Outage-Postponed

It is the exit that requires the unit to be taken out of service after (6) hours but before the end of the week (it can be postponed but during the same week), and this type of exit is only when the unit is in service.

It was agreed to be the exit that requires the unit to be removed after the next peak period instead of after (6) hours.

1-1-5 Notes when logging out:

There are two cases of testing equipment when it is being repaired or replaced. The testing period must be included in the approved classification. The recording of testing periods depends on the extent to which the unit/equipment is connected to the network or not when the tests are carried out on it.

A- In the case of Online (Synchronized):

If the unit has to be attached to a low load while performing some tests the planned off (PO), maintenance of (MO), or unplanned off (forced) [U1, U2, U3, SF] are recorded as planned low power (PD). ), low maintenance capacity (D4), or unplanned (forced) low capacity [D1], respectively. The time period for (PD), (D4), and (D1) is calculated when the test begins and ends when the test is completed.

B- In the case of Off-line (Not Synchronized):

In cases where there is no need to connect the unit to the network to perform the tests, the test period is recorded as part of the exit on which the unit is located, and the exit period ends with the end of the test or the unit entering another state.

1-2 Deratings:

1-2-1 Reduction in capacity occurs when a unit is constrained to produce a specific capacity that is less than its net capacity

2.1 Decreased capacity occurs when the unit is restricted to producing a specific capacity that is less than its maximum net capacity.

1-2-2 The calculation of low capacity begins when the unit is unable to reach (100%) of its capacity. The available capacity depends on the unit's production and does not depend on the network requirements and the time of low capacity ends when the problem causing it ends.

1-2-3 All periods of capacity decline that exceed (2%) of the maximum unit capacity and continue for a period of more than (30) minutes, shall be recorded. The recording is not made for low capacity caused by network requirements or ambient weather conditions such as outside temperatures.

It was agreed that the decrease in the capacity of more than (8%) and for a period of more than (30) minutes should be calculated in the case of operating the units on crude or heavy oil.

1-2-4 types of low capacity

They are classified into six types as follows:

Low PD of planned capacity

Planned Derating

It is a pre-planned drop incapacity for a standard/specified time period.

D4 Low maintenance capacity

Maintenance Derating

It is a maintenance capacity decline that can be deferred to the following week and calls for a unit capacity reduction before the next PO. This type is characterized by flexibility in the start time as there is no standard/specific time for its implementation period.

DE extension for low capacity

Derating Extension

An extension of the planned depletion of power (PD) or depletion of maintenance capacity (D4), beyond their expected period of time.

An extension of reduced capacity occurs when the core scope of work requires additional time to be completed. It is not possible to calculate the extension time of the capacity decline when the scope of work changes, whether due to the presence or occurrence of unforeseen problems.

Extension of DE power must be accurately timed (month, day, hour, and minute) after the planned depletion of power (PD) or maintenance depletion (D4) has ended.

D1 Unplanned decrease in power (forced) - sudden

Unplanned (Forced) Derating-Immediate

It is the reduction in power that requires immediate reduction of the unit's power.

D2 Unplanned low power (forced) - delayed

Unplanned (Forced) Derating-Delayed

It is the decline in power that requires the unit's power to be reduced sooner but within (6) hours.

It was agreed that it would be the drop that required the unit capacity to be reduced before the next peak period instead of limiting it to a period of (6) hours.

D3 Unplanned low power (emergency) - delayed

Unplanned (Forced) Derating-Postponed

It is the decrease in a capacity that does not require a decrease in the unit capacity within (6) hours but before the end of the week (it can be postponed but during the same week).

It was agreed that it is low that requires the unit capacity to be reduced after the next peak period instead of after (6) hours.

1-2-5 Observations when recording low capacity:

A- Ambient-related losses:

It is not possible to record the loss due to a change in the ambient weather conditions (or the outside temperature) for two reasons that prevent this type of recording, namely:

• Frequent and confusing the level of accuracy of registration to follow up the behavior of the low capacity of the units.

• Ease of calculating losses due to ambient weather conditions from performance equations, which is simply / the difference between the maximum capacity and the dependable capacity during a certain period.

B- System Dispatch Requirements:

Sometimes the units are running at less than their maximum capacity depending on the network requirements, and this cannot be recorded as the low capacity of the units.

Also, any work that is performed at low load under certain conditions, is not recorded as under capacity but is recorded as Unclassified Incident (NC) as will be later.

C- Power rises during start-up and decreases during shutdown

 (Ramping Up at Unit Startup and Down at Shutdown):

Each generating unit has a known time (standard/normal) to reach full load while on or low before shutting off, due to the operator's knowledge and estimate of the time the unit needs to rise and fall in load during start-up and shutdown.

If the time required for the unit to reach its maximum capacity does not exceed the known (limited) time, then no period for the unit's capacity is calculated.

If the time of arrival of the unit to its maximum capacity exceeds the specified time, then the difference between the fluctuating capacity and the ability it reached by the end of the specified time is the level of decline, and the period of low capacity is calculated from the end of the specified time until it reaches its fluctuating capacity or reaching the required capacity level from the network.

There is no account for low power in extinguishing, as each unit must be extinguished in order to achieve the safety of equipment and workers, because some units require that they be extinguished quickly, as in the event of faults, and some require that they be extinguished slowly, such as the units coming out for the planned exit.

1-3 Status Ready to Run (Reserve Shutdown - RS):

1-3-1 A situation in which the unit is ready for operation and is not connected to the network because it is not needed or sometimes because of the priority of economic operation.

1-3-2 If the unit is turned off due to any problem that causes it to go out of service, it is recorded as an Emergency Exit, Maintenance Exit, or Planned Exit and is not recorded as RS even if it is not requested by the network.

1-3-3 When some maintenance work is carried out during the RS period, the period of execution of the works is considered part of it if the work can be terminated or stopped, provided that this does not prevent the unit from:

A- Connecting to the network after the end of the normal start-up cycle.

  b- Reaching the available capacity after the end of the natural cycle of loading.

Both conditions (a and b) remain valid even if the unit is not requested by the network.

1-3-4 When some maintenance work is carried out during the RS period and the work cannot be terminated or stopped, the situation is transferred to a type of

B- If the unit becomes unable to reach its available capacity due to the lack of work and even if the unit is not requested by the network, it must start recording a period of deterioration of the capacity (Derating) while its condition continues (RS), it must be assumed that the available capacity is a result of the decline that occurred.

1-4 Noncurtailing Events - NC:

1-4-1 Any event as a result of the removal of equipment or one of the large parts of the unit or its aids from service for maintenance, testing or any other purpose and not as a result of the removal or reduced capacity. "Equipment includes transformers or boilers...etc."

1-4-2 If the generation unit is operated at less than its capacity to meet the network requirements, during this period the equipment can be taken out of service for maintenance, testing, or any other reason. It is considered (NC) if the following two conditions are met only:

a- The available capacity shall not be less than the required capacity from the network.

b- Maintenance work is terminated or stopped and the unit can reach the level of its net fluctuating power (NDC) during the normal start-up period when requested by the network.

1-5 Event Transitions:

Sometimes a succession of incidents occurs before the unit is entered into the network and each of them must be recorded separately, even if they are related to each other. The following table  shows the relationship between the facts and the details of the types of transfer allowed:

The word “yes” indicates that the conversion from one type to another in the absence of linkage is allowed and that the time of the beginning of the next type is the time of the end of the previous type, and its periods are consecutive.

The word “no” indicates that there is no relationship between successive types of events and that the time and period of each type of event must be recorded separately and not in succession.

When there is no connection to the network during the succession of two types of events and the start time of the next type is the time of the end of the previous type, in this case, it is not possible to transform until the result of the event is completed, meaning that the time that the unit naturally takes to reach the connection limit must be calculated before the completion of the transformation for the next type.

The word "included": indicates that the startup time is taken into account by the previous definitions (exit, extension to exit, startup failure, low power, ready-to-run state)

Not applicable: indicates that transferring between two types of events is not allowed and the unit must be networked before another type can occur.

1-6 Unit Generation Performance:

GMC Total Maximum Power

Gross Maximum Capacity Unit MW

It is the maximum power produced by the unit and maintained for a specified period of time and is not affected by weather conditions or low. Total Maximum Capacity (GMC) changes only after a new performance test or permanent modification/development is made on the units, and it cannot be changed due to technical problems on the units even if it persists for a long time unless the unit is permanently modified as a result of the problem.

It was agreed that the maximum total power (GMC) is: the unit capacity under the conditions specified by the International Standards Organization (ISO) "below (15) degrees Celsius at sea level and the humidity of 60 (%").

GDC Total Volatile Capacity

Gross Dependable Capacity Unit MW

It is the total capacity produced by the unit and maintained for a specified period of time and has no operational restrictions.

Total Volatile Power (GDC) From the definition: It is the total maximum power (GMC) adjusted for weather conditions.

GAG Total Actual Generated Power

Gross Actual Generation UnitMWh

It is the total actual energy produced by the unit in megawatt-hours during the period.

 GAC Maximum Capacity Available

Gross Available Capacity UnitMW

It is the largest capacity that the unit can produce when its capacity is reduced as a result of the low capacity.

 It was agreed to continue calculating the actual capacity as follows:

  TAC Total Actual Capacity

Total Actual Capacity UnitMW

The actual generation capacities of each business area are determined according to the weather conditions at a temperature of (50) degrees Celsius, as is currently applied.

NMC net maximum capacity

Net Maximum Capacity UnitMW

It is the total maximum power (GMC) minus the power used to cover the station's service or internal aid loads.

NDC Net Volatile Capacity

Net Dependable Capacity UnitMW

It is the total variable power (GDC) minus the power used to cover the station's utility or internal aid loads.

NAG net actual generated energy

Net Actual Generation UnitMWh

It is the total actual generated power (GAG) minus the power used to cover the station's service or internal auxiliary loads.

NAC Max Net Capacity

Net Available Capacity UnitMW

It is the maximum available capacity (GAC) minus the capacity used to cover station service or internal aid loads.

2- Calculations of exit time and low capacity:

SH operational hours

Service Hours

It is the sum of the unit's operating hours.

AH hours available

Available Hours

It is the sum of unit operating hours (SH) + RSH + Pumping Hours + Synchronous Condensing Hours.

Note: Pumping Hours are for water stations only.

POH planned checkout hours

Planned Outage Hours

It is the sum of the planned unit exit (PO) hours + the extension hours for the programmed exit (SE) for any planned exit (PO) on the unit.

UOH Unplanned Exit Hours

Unplanned Outage Hours

It is the sum of unit unplanned (forced) exit hours (U1,-U2,-U3) + start failure (SF) hours + maintenance off (MO) + SE extended hours for any maintenance exit (MO) on the unit .

  FOH emergency exit hours

Unplanned (Forced) Outage Hours

It is the sum of unit unplanned (forced) exit hours (U1,-U2,-U3) + startup failure (SF) hours.

MOH Service Out Hours

Maintenance Outage Hours

 It is the sum of the maintenance exit (MO) hours + the extension hours for the programmed exit (SE) for any maintenance exit (MO) on the unit.

UH Unavailable hours

Unavailable Hours

It is the sum of the planned exit hours (POH) + the unplanned exit hours (UOH)

SOH programmed exit hours

Scheduled Outage Hours

It is the sum of the planned unit exit (PO) + maintenance exit (MO) hours + the extension hours for programmed exit (SE) for any planned exit (PO) or maintenance exit (MO) on the unit.

PH hours time period

Period Hours

The number of hours of data recording period for the units available.

ESEDH Equivalent Hours of Seasonal Low

Equivalent Seasonal Derated Hours

Net highest available capacity (NMC) from the net volatile capacity (NDC)  available hours (AH) / net highest available capacity (NMC).

NMC)  AH - NDC)

NMC

EFDH

(D1, D2, D3) Equivalent hours for an emergency landing

Equivalent Unplanned(Forced) Derated Hours

It is to calculate each unplanned (forced) capacity decline (D1,-D2,-D3) independently for all units and then convert it to equivalent off hours. The calculation is done by multiplying the actual period of low capacity (hours) by the size of low capacity (megawatts) and dividing by the net highest capacity (NMC). Then all equivalent hours are summed.

Derating Hours  Size of Reduction*

NMC

Note: Includes emergency power reduction (D1, D2, D3) during the (RS) period of the unit.

 EPDH

(PD, DE) Equivalent hours of planned capacity decline

Equivalent Planned Derated Hours

Each planned power depreciation (PD, DE) is calculated independently for all units and then converted into equivalent exit hours. The calculation is done by multiplying the actual period of low power (hours) by the volume of low power (megawatts) and dividing by the net highest capacity (NMC). Then all equivalent hours are summed.

Derating Hours  Size of Reduction*

NMC

 Note: Includes planned capacity decline (PD, DE) over the period (RS) of the unit.

EUDH

(D1, D2, D3, D4, DE) Equivalent hours of unplanned low capacity

Equivalent Unplanned Derated Hours

It is to calculate each unplanned capacity decline (D1, D2, D3, D4, DE) independently for all units and then convert it to equivalent off hours. The calculation is done by multiplying the actual period of low power (hours) by the volume of low power (megawatts) and dividing by the net highest capacity (NMC). Then all equivalent hours are summed.

Derating Hours  Size of Reduction*

NMC

Note: Includes unplanned capacity decline (D1, D2, D3, D4, DE) during the RS period of the unit.

EFDHRS

(D1, D2, D3) Equivalent hours of emergency power-down during (RS)

Equivalent Planned (Forced)Derated Hours During RS

It is the calculation of each unplanned downgrade (D1, D2, D3) independently for all units and then converted to equivalent off-hours or the portion of any unplanned (forced) power down that occurs when the unit is in RS mode where it is converted to equivalent off hours. The calculation is done by multiplying the actual period of low power (hours) by the volume of low power (megawatts) and dividing by the net highest capacity (NMC). Then all equivalent hours are summed.

Derating Hours  Size of Reduction*

NMC

* The magnitude of impairment is determined by subtracting net available capacity (NAC) from the net fluctuating capacity (NDC). In the event that there is more than one capacity decline per unit, then each capacity decline is calculated on the basis of the difference between the net available capacity before and after its occurrence, and the net available capacity is recorded as a result of the decline.

 Planned exit (PO) for available units

Number of Planned Outages (PO) which occur in-service state only

It is the planned exit (PO) of the unit provided "The number of planned exit (SE) extensions is not counted when considered as part of the originally planned exit (PO).

   Number of unplanned exits (MO, U1, U2, U3) for available units

Number of Unplanned Outages (MO, U1, U2, U3) which occur in-service state only

It is the number of unplanned exits (MO, U1, U2, U3) of the available unit and does not count the number of startup failures (SF).

Number of forced exits (U1, U2, U3) for available units

Number of Unplanned (Forced) Outages (U1, U2, U3) which occurs in-service state only

It is the number of forced exits (U1, U2, U3) for the available unit and does not count the number of startup failures (SF).

Number of times for maintenance (MO) for available units

Number of Maintenance Outages (MO) which occur in-service state only

It is the number of maintenance exits (MO) for the available unit "The number of extensions to the planned exit (SE) is not counted when it is considered part of the originally planned exit (MO)."

   3- Performance indicators and equations:

3-1 Planned Exit Factor:

POF planned exit factor

Planned Outage Factor

POF planned exit factor

Planned Outage Factor

It is calculated as:

100 x Planned Outage Hours = POF

Period Hours

2-3 Unplanned Exit Factor:

UOF Unplanned Exit Factor

Unplanned Outage Factor

It is calculated as:

100 x Unplanned Outage Hours = UOF

Period Hours

3-3 Forced Exit Coefficient:

FOF Forced Exit Factor

Forced Outage Factor

It is calculated as:

100 × Unplanned (Forced) Outage Hours = FOF

Period Hours

3-4 Exit factors for maintenance:

MOF Maintenance Exit Factor

Maintenance Outage Factor

It is calculated as:

100 x Maintenance Outage Hours = MOF

Period Hours

3-5 Programmed Exit Factor:

SOF Programmed Exit Factor

Scheduled Outage Factor

It is calculated as:

100 x Scheduled Outage Hours = SOF

Period Hours

3- 6 Unavailability coefficient:

UF Unavailability Factor

Unavailability Factor

It is calculated as:

100 x Unavailable Hours = UF

Period Hours

3-7 Availability factors:

AF availability factor

Availability Factor

It is calculated as:

100 x Available Hours = AF

Period Hours

3-8 Operating Factors:

SF operating factor

Service Factor

It is calculated as:

100 x Service Hours = SF

Period Hours

3-9 Seasonal decline coefficient:

SDF Seasonal Low Coefficient

Seasonal Derating Factor

It is calculated as:

100 x Equivalent Seasonal Derated Hours = SDF

Period Hours

3-10 Unit depreciation coefficient:

UDF unit depreciation factor

Unit Derating Factor

It is calculated as:

100 x Equivalent Planned Derated Hours + Equivalent Unplanned Derated Hours = UDF

Period Hours

3-11 Equivalent Unavailability Factor:

EUF Equivalent Unavailability Factor

Equivalent Unavailability Factor

It is calculated as:

100 x Planned Outage Hours + Unplanned Outage Hours + Equivalent Planned Derated Hours +

 Equivalent Unplanned Derated Hours = EUF

Period Hours

3-12 Equivalent Availability Factor:

EAF Equivalent Existential Factor

Equivalent Availability Factor

It is calculated as:

100 x Available Hours - Equivalent Planned Derated Hours - Equivalent Unplanned Derated Hours - Equivalent Seasonal Derated Hours = EAF

Period Hours

3-13 Total Power Factor:

GCF total power factor

Gross Capacity Factor

It is calculated as:

100 x Gross Actual Generation = GCF

Period Hours × Gross Maximum Capacity

3-14 Net Power Factor:

NCF net power factor

Net Capacity Factor

It is calculated as:

100 x Net Actual Generation = NCF

Period Hours × Net Maximum Capacity

3-15 Aggregate Load Factor:

GOF Aggregate load factor

Gross Output Factor

It is calculated as:

100 x Gross Actual Generation = GOF

Service Hours × Gross Maximum Capacity

3-16 Net Load Factor:

NOF Net Load Factor

Net Output Factor

It is calculated as:

100 x Net Actual Generation = NOF

Service Hours × Net Maximum Capacity

3-17 Emergency Exit Rate:

FOR EMERGENCY EXIT RATE

Forced Outage Rate

It is calculated as:

100 x Unplanned (Forced) Outage Hours = FOR

Unplanned (Forced) Outage Hours + Service Hours

3-18 Equivalent Emergency Exit Rate:

EFOR Equivalent Emergency Exit Rate

Equivalent Forced Outage Rate

It is calculated as:

100 x Unplanned (Forced) Outage Hours + Equivalent Unplanned (Forced) Derated Hours = EFOR

Unplanned (Forced) Outage Hours + Service Hours + Equivalent Unplanned (Forced) Derated Hours during Reserve Shutdowns (RS) Only

3-19 average hours of service:

ART average service hours

Average Run Time

It is calculated as:

100 x Service Hours = ART

Actual Unit Starts

3-20 Start-up reliability factor:

SR Starting Reliability Factor

It is calculated as:

100 x Actual Unit Starts = SR

Attempted Unit Starts

3-21 Mean Service Time to Outage

3-21-1 Average operating hours to planned exit:

MSTPO average operating hours to the planned exit

Mean Service Time to Planned Outage

It is calculated as follows:

Service Hours MSTPO =

Number of Planned Outages

(Which Occur from the in-service state only)

3-21-2 Average operating hours to unplanned exit:

MSTUO Average Operating Hours to Unplanned Checkout

Mean Service Time to Unplanned Outage

It is calculated as follows:

Service Hours MSTUO =

Number of Unplanned Outages

(Which Occur from the in-service state only)

3-21-3 Average operational hours to emergency exit:

MSTFO Average Operational Hours to Emergency Exit

Mean Service Time to Forced Outage

It is calculated as follows:

Service Hours MSTFO =

Number of Unplanned(Forced) Outages

(Which Occur from the in-service state only)

3-21-4 Average hours of operation to exit for maintenance:

MSTMO Average Hours Operational to Checkout for Maintenance

Mean Service Time to Maintenance Outage

It is calculated as follows:

3-22-3 Average period of forced exit:

MFOD Average Emergency Exit Period

Mean Forced Outage Duration

It is calculated as follows:

Unplanned(Forced) Outage Hours MFOD =

Number of Unplanned(Forced) Outages

(Which Occur from the in-service state only)

3-22-4 Average maintenance exit period:

MMOD Average maintenance checkout period

Mean Maintenance Outage Duration

It is calculated as follows:

Maintenance Outage Hours MMOD =

Number of Maintenance Outages

(Which Occur from the in-service state only)

Service Hours MSTMO =

Number of Maintenance Outages

(Which Occur from the in-service state only)

3- 22 Mean Outage Duration

3-22-1 Average planned exit period:

MPOD average planned exit period

Mean Planned Outage Duration

It is calculated as follows:

Planned Outage Hours MPOD =

Number of Planned Outages

(Which Occur from the in-service state only)

3-22-2 Average Unplanned Exit Period:

MUOD average period of