Microprocessor based motor protective relay with half wave sampling

Claim 2

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical system: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IC(W+240°) in accordance with the following relationships: IP(W)=f[IA((W), IB(W+120°), IC(W+240°)] IP(W+120°)=f[IA(W+120°), IB(W+240°), IC(W)] IP(W+240°)=f[IA(W+240°), IB(W), IC(W+120°)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°) for performing said operation.

Claim 3

The combination as claimed in claim 1 wherein said storage means comprises random access memory means and wherein said stored values of electrical phase currents are retrievable by one-bit incrementation of storage addresses for each stored value of electrical phase currents.

Claim 4

The combination as claimed in claim 1 wherein 0°≦W≦360°.

Claim 5

The combination as claimed in claim 1 wherein: ##EQU10##

Claim 6

Electrical apparatus which performs an operation as a function of negative sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IN(W)=f[IA(W), IB(W+240°), IC(W+120°)] IN(W+120°)=f[IA(W+120°), IB(W), IC(W+240°)] IN(W+240°)=f[IA(W+240°), IB(W+120°), IC(W)]; and means responsive to the presence of IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 7

Electrical apparatus which performs an operation as a function of negative sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IN(W)=f[IA(W), IB(W+240°), IC(W+120°)] IN(W+120°)=f[IA(W+120°), IB(W), IC(W+240°)] IN(W+240°)=f[IA(W+240°), IB(W+120°), IC(W)]; and means responsive to the presence of IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 8

The combination as claimed in claim 5 wherein said storage means comprises random access memory means and wherein said stored values of electrical phase currents are retrievable by one-bit incrementation of storage addresses for each stored value of electrical phase currents.

Claim 9

The combination as claimed in claim 5 wherein 0°≦W≦360°.

Claim 10

The combination as claimed in claim 5 wherein: ##EQU11##

Claim 11

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for storing said values of electrical phase currents; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IP(W)=f[IA(W), IB(W+120°), IC(W+240°)] [IP(W)+120°)=f[IA(W+120°), IB(W+240°), IC(W)]] IP(W+120°)=f[IA(W+120°), IB(W+240°), IC(W) IP(W+240°)=f[IA(W+240°), IB(W), IC(W+120°)] IN(W)=f[IA(W), IB(W+240°), IC(W+120°)] IN(W+120°)=f[IA(W+120°), IB(W), IC(W+240°)] IN(W+240°)=f[IA(W+240°), IB(W+120°), IC(W)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 12

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for storing said values of electrical phase currents; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IP(W)=f[IA(W), IB(W+120°), IC(W+240°)] [IP(W)+120°)=f[IA(W+120°), IB(W+240°), IC(W)]] IP(W+120°)=f[IA(W+120°), IB(W+240°), IC(W) IP(W+240°)=f[IA(W+240°), IB(W), IC(W+120°)] IN(W)=f[IA(W), IB(W+240°), IC(W+120°)] IN(W+120°)=f[IA(W+120°), IB(W), IC(W+240°)] IN(W+240°)=f[IA(W+240°), IB(W+120°), IC(W)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 13

The combination as claimed in claim 9 wherein said storage means comprises random access memory means and where said stored values of electrical phase currents are retrievable by one-bit incrementation of storage addresses for each stored value of electrical phase currents.

Claim 14

The combination as claimed in claim 9 wherein 0°≦W≦360°.

Claim 15

The combination as claimed in claim 9 wherein: ##EQU12##

Claim 16

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for contiguously storing said values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) from only said contiguously stored values of electrical phase currents; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 17

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for contiguously storing said values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) from only said contiguously stored values of electrical phase currents; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 18

The combination as claimed in claim 13 wherein said storage means comprises random access memory means and wherein said contiguously stored values of electrical phase currents are retrievable by one-bit incrementation of storage addresses for each stored value of electrical phase currents.

Claim 19

The combination as claimed in claim 13 where 0°≦W≦360°.

Claim 20

The combination as claimed in claim 13 wherein: ##EQU13##

Claim 21

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical voltage VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical system: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical voltages; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components VP(W), VP(W+120°), VC(W+240°) in accordance with the following relationships: VIP(W)=f[VA(W), VB(W+120°), VC(W+240°)] VP(W+120°)=f[VA(W+120°), VB(W+240°), VC(W)] VP(W+240°)=f[VA(W+240°), VB(W), VC(W+120°)]; and means responsive to the presence of VP(W), VP(W+120°), VP(W+240°), for performing said operation.

Claim 22

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical voltage VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical system: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical voltages; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components VP(W), VP(W+120°), VC(W+240°) in accordance with the following relationships: VIP(W)=f[VA(W), VB(W+120°), VC(W+240°)] VP(W+120°)=f[VA(W+120°), VB(W+240°), VC(W)] VP(W+240°)=f[VA(W+240°), VB(W), VC(W+120°)]; and means responsive to the presence of VP(W), VP(W+120°), VP(W+240°), for performing said operation.

Claim 23

The combination as claimed in claim 17 wherein said storage means comprises random access memory means and wherein said stored values of electrical voltages are retrievable by one-bit incrementation of storage addresses for each stored value of electrical voltages.

Claim 24

The combination as claimed in claim 17 wherein 0°≦W≦360°.

Claim 25

The combination as claimed in claim 17 wherein: ##EQU14##

Claim 26

The combination as claimed in claim 17 wherein said voltage is phase voltage.

Claim 27

The combination as claimed in claim 17 wherein said voltage is line to neutral voltage.

Claim 28

Electrical apparatus which performs an operation as a function of negative sequence symmetrical components of the electrical voltages VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical systems: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for value of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said value of electrical voltages; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable cooperable with said storage means for determining the negative sequence symmetrical components components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IN(W)=f[VA(W), VB(W+240°), VC(W+120°)] IN(W+120°)=f[VA(W+120°), VB(W), VC(W+240°)] IN(W+240°)=f[VA(W+240°), VB(W+120), VC(W)]; and means responsive to the presence of IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 29

Electrical apparatus which performs an operation as a function of negative sequence symmetrical components of the electrical voltages VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical systems: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for value of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said value of electrical voltages; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; calculating means cooperable cooperable with said storage means for determining the negative sequence symmetrical components components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IN(W)=f[VA(W), VB(W+240°), VC(W+120°)] IN(W+120°)=f[VA(W+120°), VB(W), VC(W+240°)] IN(W+240°)=f[VA(W+240°), VB(W+120), VC(W)]; and means responsive to the presence of IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 30

The combination as claimed in claim 23 wherein said storage means comprises random access memory means and wherein said stored values of electrical voltages are retrievable by one-bit incrementation of storage addresses for each stored value of electrical voltages.

Claim 31

The combination as claimed in claim 23 wherein 0°≦W≦360°.

Claim 32

The combination as claimed in claim 23 wherein: ##EQU15##

Claim 33

The combination as claimed in claim 23 wherein said voltage is phase voltage.

Claim 34

The combination as claimed in claim 23 wherein said voltage is line to neutral voltage.

Claim 35

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical voltages VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical systems: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for storing said values of electrical voltages; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IP(W)=f[VA(W), VB(W+120°), VC(W+240°)] [IP(W)+120°)=f[VA(W+120°), VB(V+240°),VC(W)]] IP(W+120°)=f[VA+120°), VB(W+240°), VC(W) IP(W+240°)=f[VA(W+240°), VB(W), VC(W+120°)] IN(W)=f[VA(W), VB(W+240°), VC(W+120°)] IN(W+120°)=f[VA(W+240°)] IN(W+240°)=f[V(W+240°), VB(W+120°), VC(W)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 36

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical voltages VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical systems: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for storing said values of electrical voltages; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) in accordance with the following relationship: IP(W)=f[VA(W), VB(W+120°), VC(W+240°)] [IP(W)+120°)=f[VA(W+120°), VB(V+240°),VC(W)]] IP(W+120°)=f[VA+120°), VB(W+240°), VC(W) IP(W+240°)=f[VA(W+240°), VB(W), VC(W+120°)] IN(W)=f[VA(W), VB(W+240°), VC(W+120°)] IN(W+120°)=f[VA(W+240°)] IN(W+240°)=f[V(W+240°), VB(W+120°), VC(W)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing said operation.

Claim 37

The combination as claimed in claim 9 wherein said storage means comprises random access memory means and where said stored values of electrical voltages are retrievable by one-bit incrementation of storage addresses for each stored value of electrical voltages.

Claim 38

The combination as claimed in claim 30 wherein 0°≦W≦360°.

Claim 39

The combination as claimed in claim 30 wherein: ##EQU16##

Claim 40

The combination as claimed in claim 30 wherein said voltage is phase voltage.

Claim 41

The combination as claimed in claim 30 wherein said voltage is line to neutral voltage.

Claim 42

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical voltages VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical systems: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for contiguously storing said values of electrical voltages; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) from only said contiguously stored values of electrical voltages; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W'120°) IN(W+240°) for performing said operation.

Claim 43

Electrical apparatus which performs an operation as a function of positive and negative sequence symmetrical components of the electrical voltages VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical systems: VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°), VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for contiguously storing said values of electrical voltages; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative sequence symmetrical components IN(W), IN(W+120°), IN(W+240°) from only said contiguously stored values of electrical voltages; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W'120°) IN(W+240°) for performing said operation.

Claim 44

The combination as claimed in claim 35 wherein said storage means comprises random access memory means and wherein said contiguously stored values of electrical voltages are retrievable by one-bit incrementation of storage addresses for each stored value of electrical voltages.

Claim 45

The combination as claimed in claim 35 wherein 0°≦W≦360°.

Claim 46

The combination as claimed in 35 wherein: ##EQU17##

Claim 47

The combination as claimed in claim 35 wherein said voltage is phase voltage.

Claim 48

The combination as claimed in claim 35 wherein said voltage is line to neutral voltage.

Claim 49

Electrical motor monitor and control apparatus which safeguards an electrical motor as a function of positive and negative sequence symmetrical components of the electrical motor phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase motor currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W'120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for contiguously storing said values of electrical motor phase currents; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative symmetrical components IN(W), IN(W+120°) IN(W+240°) from only said contiguously stored values of electrical motor phase currents; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing an operation which safeguards said motor.

Claim 50

Electrical motor monitor and control apparatus which safeguards an electrical motor as a function of positive and negative sequence symmetrical components of the electrical motor phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase motor currents in said three-phase electrical systems: IA(W), IB(W), IC(W), IA(W+120°), IB(W'120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more negative of the two compared values with the more positive of the two compared values; storage means cooperable with said sensing means for contiguously storing said values of electrical motor phase currents; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IP(W+240°) and the negative symmetrical components IN(W), IN(W+120°) IN(W+240°) from only said contiguously stored values of electrical motor phase currents; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°), IN(W), IN(W+120°), IN(W+240°) for performing an operation which safeguards said motor.

Claim 51

The combination as claimed in claim 41 wherein said storage means comprises random access memory means and wherein said contiguously stored values of electrical motor phase currents are retrievable by one-bit incrementation of storage addresses for each stored value of electrical phase currents.

Claim 52

The combination as claimed in claim 41 wherein 0°≦W≦360°.

Claim 53

The combination as claimed in claim 41 wherein: ##EQU18##

Claim 54

The combination as claimed in claim 43 wherein W is taken in 10° sample intervals.

Claim 55

The combination as claimed in claim 45 wherein all 36 values of IP 2 thus sampled are added to form IP 2 TOTAL.

Claim 56

The combination as claimed in claim 45 wherein all 36 values IN 2 thus sampled are added to four INTOTAL 2 .

Claim 57

The combination as claimed in claim 46 wherein all 36 values IN 2 thus sampled are added to four INTOTAL 2 .

Claim 58

The combination as claimed in claim 48 wherein said electrical motor is safeguarded as a function of IRMS 2 , where IRMS 2 =IP 2 TOTAL+IN 2 TOTAL.

Claim 59

The combination as claimed in claim 48 wherein said electrical motor is safeguarded as a function of IEFF 2 , where IEFF 2 =IPTOTAL 2 +6INTOTAL 2 .

Claim 60

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical system; IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for contiguously storing said discrete values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more positive of the two compared values with the more negative of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IC(W+240°) in accordance with the following relationships: IP(W)=f[IA(W), IB(W+120°), IC(W+240°)] IP(W+120°)=f[IA(W+120°), IB(W+240°), IC(W)] IP(W+240°)=f[IA(W+240°), IB(W), IC(W+120°)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°) for performing said operation.

Claim 61

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical phase currents IA, IB, and IC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical phase currents in said three-phase electrical system; IA(W), IB(W), IC(W), IA(W+120°), IB(W+120°), IC(W+120°), IA(W+240°), IB(W+240°), IC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for contiguously storing said discrete values of electrical phase currents; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more positive of the two compared values with the more negative of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components IP(W), IP(W+120°), IC(W+240°) in accordance with the following relationships: IP(W)=f[IA(W), IB(W+120°), IC(W+240°)] IP(W+120°)=f[IA(W+120°), IB(W+240°), IC(W)] IP(W+240°)=f[IA(W+240°), IB(W), IC(W+120°)]; and means responsive to the presence of IP(W), IP(W+120°), IP(W+240°) for performing said operation.

Claim 62

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical voltage VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical system; VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°) VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical voltages; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more positive of the two compared values with the more negative of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components VP(W), VP(W+120°), VC(W+240°) in accordance with the following relationships: VIP(W)=f[VA(W), VB(W+120°), VC(W+240°)] VP(W+120°)=f[VA(W+120°), VB(W+240°), VC(W)] VP(W+240°)=f[VA(W+240°), VB(W), VC(W+120°)]; and means response to the presence of VP(W), VP(W+120°), VP(W+240°), for performing said operation.

Claim 63

Electrical apparatus which performs an operation as a function of positive sequence symmetrical components of the electrical voltage VA, VB, and VC in a three-phase electrical system, comprising: sensing means for determining values for the following electrical voltages in said three-phase electrical system; VA(W), VB(W), VC(W), VA(W+120°), VB(W+120°), VC(W+120°), VA(W+240°) VB(W+240°), VC(W+240°), for values of W and for values of W+180° where W is an electrical angle; storage means cooperable with said sensing means for storing said values of electrical voltages; comparison means cooperable with said storage means for comparing common phase values which are 180° separated from each other and for replacing in said storage means that value which is the more positive of the two compared values with the more negative of the two compared values; calculating means cooperable with said storage means for determining the positive sequence symmetrical components VP(W), VP(W+120°), VC(W+240°) in accordance with the following relationships: VIP(W)=f[VA(W), VB(W+120°), VC(W+240°)] VP(W+120°)=f[VA(W+120°), VB(W+240°), VC(W)] VP(W+240°)=f[VA(W+240°), VB(W), VC(W+120°)]; and means response to the presence of VP(W), VP(W+120°), VP(W+240°), for performing said operation.