ANSI Standard Device Numbers-Electrical Power System

1 - Master Element

2 - Time-delay Starting or Closing Relay

3 - Checking or Interlocking Relay, complete Sequence

4 - Master Protective

5 - Stopping Device, Emergency Stop Switch

6 - Starting Circuit Breaker

7 - Rate of Change Relay

8 - Control Power Disconnecting Device

9 - Reversing Device

10 - Unit Sequence Switch

11 - Multifunction Device

12 - Overspeed Device

13 - Synchronous-Speed Device

14 - Under speed Device

15 - Speed or Frequency Matching Device

16 - Data Communications Device

17 - Shunting or Discharge Switch

18 - Accelerating or Decelerating Device

19 - Starting-to-Running Transition Contactor

20 - Electrically-Operated Valve ( Solenoid Valve )

21 - Distance Relay

21G - Ground Distance

21P - Phase Distance

22 – Equalizer circuit breaker

23 – Temperature control device, Heater

24 – Volts per hertz relay

25 – Synchronizing or synchronism-check device

26 – Apparatus thermal device, Temperature Switch

27 – Undervoltage relay

27P - Phase Undervoltage

27S - DC undervoltage relay

27TN - Third Harmonic Neutral Undervoltage

27TN/59N - 100% Stator Earth Fault

27X - Auxiliary Undervoltage

27 AUX - Undervoltage Auxiliary Input

27/27X - Bus/Line Undervoltage

27/50 - Accidental Generator Energization

28 - Flame Detector

29 - Isolating Contactor

30 - Annunciator Relay

31 - Separate Excitation Device

32 - Directional Power Relay

32L - Low Forward Power

32H - High Directional Power

32N - Watt metric Zero-Sequence Directional

32P - Directional Power

32R - Reverse Power

33 - Position Switch

34 - Master Sequence Device

35 - Brush-Operating or Slip-ring Short Circuiting Device

36 - Polarity or Polarizing Voltage Device

37 - Undercurrent or Underpower Relay

37P - Underpower

38 - Bearing Protective Device / Bearing Rtd

39 - Mechanical Condition Monitor ( Vibration )

40 - Field Relay / Loss of Excitation

41 - Field Circuit Breaker

42 - Running Circuit Breaker

43 - Manual Transfer or Selector Device

44 - Unit Sequence Starting Relay

45 - Fire Detector

46 - Reverse-Phase or Phase Balance Current Relay or Stator Current Unbalance

47 - Phase-Sequence or Phase Balance Voltage Relay

48 - Incomplete Sequence Relay / Blocked Rotor

49 - Machine or Transformer Thermal Relay / Thermal Overload

49RTD - RTD Biased Thermal Overload

50 - Instantaneous Overcurrent Relay

50BF - Breaker Failure

50DD - Current Disturbance Detector

50EF - End Fault Protection

50G - Ground Instantaneous Overcurrent

50IG - Isolated Ground Instantaneous Overcurrent

50LR - Acceleration Time

50N - Neutral Instantaneous Overcurrent

50NBF - Neutral Instantaneous Breaker Failure

50P - Phase Instantaneous Overcurrent

50SG - Sensitive Ground Instantaneous Overcurrent

50SP - Split Phase Instantaneous Current

50Q - Negative Sequence Instantaneous Overcurrent

50/27 - Accidental Energization

50/51 - Instantaneous / Time-delay Overcurrent relay

50Ns/51Ns - Sensitive earth-fault protection

50/74 - Ct Trouble

50/87 - Instantaneous Differential

51 - AC Time Overcurrent Relay

51G - Ground Time Overcurrent

51LR - AC inverse time overcurrent (locked rotor) protection relay

51N - Neutral Time Overcurrent

51P - Phase Time Overcurrent

51R - Locked / Stalled Rotor

51V - Voltage Restrained Time Overcurrent

51Q - Negative Sequence Time Overcurrent

52 – AC circuit breaker

52a - AC circuit breaker position (contact open when circuit breaker open)

52b - AC circuit breaker position (contact closed when circuit breaker open)

53 - Exciter or Dc Generator Relay

54 - Turning Gear Engaging Device

55 - Power Factor Relay

56 - Field Application Relay

57 - Short-Circuiting or Grounding Device

58 - Rectification Failure Relay

59 - Overvoltage Relay

59B - Bank Phase Overvoltage

59P - Phase Overvoltage

59N - Neutral Overvoltage

59NU - Neutral Voltage Unbalance

59P - Phase Overvoltage

59X - Auxiliary Overvoltage

59Q - Negative Sequence Overvoltage

60 - Voltage or Current Balance Relay

60N - Neutral Current Unbalance

60P - Phase Current Unbalance

61 - Density Switch or Sensor

62 - Time-Delay Stopping or Opening Relay

63 - Pressure Switch Detector

64 - Ground Protective Relay

64F - Field Ground Protection

64R – Rotor earth fault

64REF – Restricted earth fault differential

64S – Stator earth fault

64S - Sub-harmonic Stator Ground Protection

64TN - 100% Stator Ground

65 - Governor

66 - Notching or Jogging Device/Maximum Starting Rate/Starts Per Hour/Time Between Starts

67 - AC Directional Overcurrent Relay

67G - Ground Directional Overcurrent

67N - Neutral Directional Overcurrent

67Ns – Earth fault directional

67P - Phase Directional Overcurrent

67SG - Sensitive Ground Directional Overcurrent

67Q - Negative Sequence Directional Overcurrent

68 - Blocking Relay / Power Swing Blocking

69 - Permissive Control Device

70 - Rheostat

71 - Liquid Switch, Level Switch

72 - DC Circuit Breaker

73 - Load-Resistor Contactor

74 - Alarm Relay

75 - Position Changing Mechanism

76 - DC Overcurrent Relay

77 - Telemetering Device, Speed Sensor

78 - Phase Angle Measuring or Out-of-Step Protective Relay

78V - Loss of Mains

79 - AC Reclosing Relay / Auto Reclose

80 - Liquid or Gas Flow Relay

81 - Frequency Relay

81O - Over Frequency

81R - Rate-of-Change Frequency

81U - Under Frequency

82 - DC Reclosing Relay

83 - Automatic Selective Control or Transfer Relay

84 - Operating Mechanism

85 - Pilot Communications, Carrier or Pilot-Wire Relay

86 - Lock-Out Relay, Master Trip Relay

87 - Differential Protective Relay

87B - Bus Differential

87G - Generator Differential

87GT - Generator/Transformer Differential

87L - Segregated Line Current Differential

87LG - Ground Line Current Differential

87M - Motor Differential

87O - Overall Differential

87PC - Phase Comparison

87RGF - Restricted Ground Fault

87S - Stator Differential

87S - Percent Differential

87T - Transformer Differential

87V - Voltage Differential

88 - Auxiliary Motor or Motor Generator

89 - Line Switch

90 - Regulating Device

91 - Voltage Directional Relay

92 - Voltage And Power Directional Relay

93 - Field-Changing Contactor

94 - Tripping or Trip-Free Relay

95 – For specific applications where other numbers are not suitable

96 – Transmitter

97 – For specific applications where other numbers are not suitable

98 – For specific applications where other numbers are not suitable

99 – For specific applications where other numbers are not suitable

Performance Ratio(PR)-A quality Factor of Solar power plant

• The Performance Ratio is used frequently to compare the efficiency of grid-connected PV systems at different loca­tions and with different module types and it is one of the most important variables for evaluating the efficiency of a PV plant.

• PR is the Ratio of Effective Produced Energy to Ideal Energy Yield at STC Condition. As it’s a Ratio it is Unit less and globally it is being denoted as a Percentage value.

  PR  =  E_Grid  /  (GlobInc * PnomPV)
  

where: 

E_Gri =Available energy to the grid 

GlobInc =Global Irradiation incident on collector plane.

PnomPV= the STC installed power

• The closer the Performance ratio  value near to 100%,the power plant is more efficiently operating.The 100% performance ratio is not possible due to losses happening in solar power plant during their operation.

• While calculating the PR all the losses like Optical losses PV array Losses DC to AC conversion losses and the other System losses are taken into Account.

Types of Performance ratio

1. STC Equivalent PR
   It is determined by adjusting the power at each recording interval to compensate for difference between the actual PV module temperature and the STC reference temperature. This method normally used when the System PR is to be measured at a short duration of day time.
2. Annual Temperature corrected PR                                                                                               Here PR is calculated by adjusting the reporting period with respect to power to compensate for the difference between the actual PV module Temperature and the expected annual average module temperature.

• Annual Temperature correction is significant when the Annual PR is required to be Validated for within 15 to 20 days of operation.
  

Calculation of the performance ratio for an analysis period of 1 year

The following parameters are there for 63kWp power plant.

E_Gri =104971 kWh

GlobInc =2164.3 kWh/M2

PnomPV=63kWp

The PR can be calculated as:

PR  =  E_Grid  /  (GlobInc * PnomPV)=104971/(2164.3*63)= 0.7698 OR 78.98%

Which factors influence the performance ratio?

• Environmental factors
  

1. Temperature of the PV module:Performance on the temperature of the PV module. At lower temperatures, a PV module is especially efficient. For example, the PV module is cold when the sky is occluded in winter and if full solar irradiation is incident on the cold PV module, then it operates very efficiently. This can generate a high performance ratio value briefly. After a certain time, the PV module heats up and the performance starters decreasing.
2. Solar irradiation and power dissipation:The solar radiation is not same through the day.In the morning and evening time,the radiation is low as compare to other part of the day.
   
3. The measuring gauge  is in the shade or soiled:This will leads to wrong reading of real time solar radiation measurement.It may cause a PR value more than 100% sometimes.
   
4. PV module in the shade or soiled
   

• Other factors

1. Recording period:It can be Day,Week,Month or year.
2.  Conduction losses:These losses are nothing but DC and AC cable from module to point of connection to the grid.These are depends on the type of cable and conducting material (Copper and Aluminum)of cable.
3. Efficiency factor of the PV modules:This has the most influence on the performance ratio of PV plant.Higher the efficiency of PV modules,Higher the Performance ration.The new technological advancement in Solar Module manufacturing like MONO-PERC,Half cut cells etc. played a vital role in overall  efficiency increment of.PV module.
4. Efficiency factor of the inverter:Normally the efficiency of PV on Grid inverters is more than 97%.
   
5. Degradation of the solar cells:The age-related degradation of the solar cells results in a lower PR value over time. Poly crystalline solar cells age up to 20 % in 25 years but advancement in manufacturing technology of PV modules will decrease this degradation.
6. Orientation of the measuring gauge:If the PV plant includes a measuring gauge and this is not correspondingly aligned with the PV modules, this can result in PV values of over 100 % due to different solar irradiation.