08 - Device Coordination

ETAP 5.0 Protective Device Coordination

Copyright 2004 Operation Technology, Inc.

Agenda • OC Protective Device Coordination – Concepts & Applications

• STAR 5.0.0 Overview – Features & Capabilities • STAR Example 1

– Advance Topics • STAR Example 2

– PD Sequence of Operation – Device Libraries – ETAP ARTTS Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 2

Definition • Overcurrent Coordination – A systematic study of current responsive devices in an electrical power system.

Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 3

Objective • To determine the ratings and settings of fuses, breakers, relay, etc. • To isolate the fault or overloads.


Slide 4

Criteria • Economics • Available Measures of Fault • Operating Practices • Previous Experience


Slide 5

Design • Open only PD upstream of the fault or overload • Provide satisfactory protection for overloads • Interrupt SC as rapidly (instantaneously) as possible • Comply with all applicable standards and codes • Plot the Time Current Characteristics of different PDs Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 6

Analysis When: • New electrical systems • Plant electrical system expansion/retrofits • Coordination failure in an existing plant


Slide 7

Protection vs. Coordination • Coordination is not an exact science • Compromise between protection and coordination – Reliability – Speed – Performance – Economics – Simplicity Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 8

Protection • Prevent injury to personnel • Minimize damage to components – Quickly isolate the affected portion of the system – Minimize the magnitude of available short-circuit


Slide 9

Spectrum Of Currents • Load Current – Up to 100% of full-load – 115-125% (mild overload)

• Overcurrent – Abnormal loading condition (Locked-Rotor)

• Fault Current – Fault condition – Ten times the full-load current and higher Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 10

Coordination • Limit the extent and duration of service interruption • Selective fault isolation • Provide alternate circuits


Slide 11

Coordination C t

D B

A A C

D

B

I


Slide 12

Equipment • Motor • Transformer • Generator • Cable • Busway Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 13

Capability / Damage Curves 2

It

t

I2t

I2t

I22t

Motor Gen

Xfmr

Cable

I


Slide 14

Transformer Category ANSI/IEEE C-57.109

Minimumnameplate (kVA) Category Single-phase Three-phase I 5-500 15-500 II 501-1667 501-5000 1668-10,000 5001-30,000 III IV above 1000 above 30,000


Slide 15

Infrequent Fault Incidence Zones for Category II & III Transformers Source Transformer primary-side protective device (fuses, relayed circuit breakers, etc.) may be selected by reference to the infrequent-faultincidence protection curve Infrequent-Fault Incidence Zone*

Category II or III Transformer Fault will be cleared by transformer primary-side protective device Optional main secondary –side protective device. May be selected by reference to the infrequent-faultincidence protection curve Fault will be cleared by transformer primary-side protective device or by optional main secondaryside protection device Feeder protective device

Frequent-Fault Incidence Zone*

Fault will be cleared by feeder protective device Feeders

* Should be selected by reference to the frequent-fault-incidence protection curve or for transformers serving industrial, commercial and institutional power systems with secondary-side conductors enclosed in conduit, bus duct, etc., the feeder protective device may be selected by reference to the infrequent-fault-incidence protection curve. Source: IEEE C57 Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 16

Transformer FLA

200

t (sec)

Thermal I2t = 1250

(D-D LL) 0.87

Infrequent Fault (D-R LG) 0.58

2

Frequent Fault

Mechanical K=(1/Z)2t Inrush

2.5


Isc

25

I (pu)

Slide 17


Slide 18

Transformer Protection MAXIMUM RATING OR SETTING FOR OVERCURRENT DEVICE PRIMARY SECONDARY Over 600 Volts Over 600 Volts 600 Volts or Below Transformer Rated Impedance

Circuit Breaker Setting

Fuse Rating

Circuit Breaker Setting

Fuse Rating

Circuit Breaker Setting or Fuse Rating

Not more than 6%

600 %

300 %

300 %

250%

125% (250% supervised)

More than 6% and not more than 10%

400 %

300 %

250%

225%

125% (250% supervised)

Table 450-3(a)


source: NEC

Slide 19

Protective Devices • Fuse • Relay (50/51 P, N, G, SG, 51V, 67, 46, 79, 21, …) • Thermal Magnetic • Low Voltage Solid State Trip • Electro-Mechanical • MCP • Overload Heater Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 20

Fuse • Non Adjustable Device • Continuous and Interrupting Rating • Voltage Levels • Characteristic Curves – Min. Melting – Total Clearing

• Application Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 21

Total Clearing Time Curve

Minimum Melting Time Curve


Slide 22

Current Limiting Fuse (CLF) • Limits the peak current of short-circuit • Reduces magnetic stresses (mechanical damage) • Reduces thermal energy


Slide 23

Peak Let-Through Amperes

Let-Through Chart 15% PF (X/R = 6.6) 230,000

300 A 100 A

12,500

60 A

5,200

100,000

Symmetrical RMS Amperes Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 25

Fuse Generally: • CLF is a better short-circuit protection • Non-CLF (expulsion fuse) is a better Overload protection


Slide 26

Selectivity Criteria Typically: • Non-CLF:

140% of full load

• CLF:

150% of full load


Slide 27

Molder Case CB • Thermal-Magnetic

Types

• Magnetic Only

• Frame Size

• Integrally Fused

• Trip Rating

• Current Limiting

• Interrupting Capability

• High Interrupting Capacity

• Voltage


Slide 28

Thermal Maximum

Thermal Minimum

Magnetic (instantaneous)


Slide 29

LVPCB • Voltage and Frequency Ratings • Continuous Current / Frame Size – Override (12 times cont. current)

• Interrupting Rating • Short-Time Rating (30 cycle) • Fairly Simple to Coordinate


Slide 30

LT PU

CB 2

CB 1

CB 2

LT Band

480 kV

ST PU

CB 1

IT If =30 kA ST Band

Motor Protection • Motor Starting Curve • Thermal Protection • Locked Rotor Protection • Fault Protection


Slide 32

Motor Overload Protection (NEC Art 430-32)

• Thermal O/L (Device 49) • Motors with SF not less than 1.15 – 125% of FLA

• Motors with temp. rise not over 40 – 125% of FLA

• All other motors – 115% of FLA Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 33

Locked Rotor Protection • Thermal Locked Rotor (Device 51) • Starting Time (TS < TLR) • LRA – LRA sym – LRA asym (1.5-1.6 x LRA sym) + 10% margin


Slide 34

Fault Protection (NEC Art 430-52) • Non-Time Delay Fuses – 300% of FLA

• Dual Element (Time-Delay Fuses) – 175% of FLA

• Instantaneous Trip Breaker – 800% of FLA*

• Inverse Time Breakers – 250% of FLA

*MCPs can be set higher Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 35

(49) 2 IT

tLR

O/L

MCP

(51)

ts Starting Curve

MCP (50)

LRAs

LRAasym

200 HP

Overcurrent Relay • Time-Delay (51 – I>) • Short-Time Instantaneous ( I>>) • Instantaneous (50 – I>>>) • Electromagnetic (induction Disc) • Solid State (Multi Function / Multi Level) • Application


Slide 37

Time-Overcurrent Unit • Ampere Tap Calculation – Ampere Pickup (P.U.) = CT Ratio x A.T. Setting – Relay Current (IR) = Actual Line Current (IL) / CT Ratio – Multiples of A.T. CT

IL

= IR/A.T. Setting = IL/(CT Ratio x A.T. Setting)

IR 51


Slide 39

Instantaneous Unit • Instantaneous Calculation – Ampere Pickup (P.U.) = CT Ratio x IT Setting – Relay Current (IR) = Actual Line Current (IL) / CT Ratio – Multiples of IT CT

IL

= IR/IT Setting = IL/(CT Ratio x IT Setting)

IR 50


Slide 40

Relay Coordination • Time margins should be maintained between T/C curves • Adjustment should be made for CB opening time • Shorter time intervals may be used for solid state relays • Upstream relay should have the same inverse T/C characteristic as the downstream relay (CO-8 to CO-8) or be less inverse (CO-8 upstream to CO-6 downstream) • Extremely inverse relays coordinates very well with CLFs Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 41

Fixed Points Points or curves which do not change regardless of protective device settings: • Motor starting curves • Transformer damage curves & inrush points • Cable damage curves • SC maximum fault points • Cable ampacities Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 42

Situation 4.16 kV CT 800:5

50/51

Relay: IFC 53

CB

Cable CU - EPR

1-3/C 500 kcmil

Isc = 30,000 A DS

5 MVA 6%

Calculate Relay Setting (Tap, Inst. Tap & Time Dial) For This System


Slide 43

Solution Transformer:

5,000kVA = 694 A 3 × 4.16kV 5 IR = IL × = 4.338 A 800

IL =

I Inrsuh = 12 × 694 = 8,328 A Set Relay:

IL IR R

CT

125% × 4.338 = 5.4 A TAP = 6.0 A TD = 1

(6/4.338 = 1.38)

Inst (50) = 8,328 ×

5 = 52.1 A => 55 A 800


Slide 44

Question What is ANSI Shift Curve?


Slide 45

Answer • For delta-delta connected transformers, with line-to-line faults on the secondary side, the curve must be reduced to 87% (shift to the left by a factor of 0.87) • For delta-wye connection, with single line-toground faults on the secondary side, the curve values must be reduced to 58% (shift to the left by a factor of 0.58) Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 46

Question What is meant by Frequent and Infrequent for transformers?


Slide 47

Answer Infrequent Fault Incidence Zones for Category II & III Transformers Source Transformer primary-side protective device (fuses, relayed circuit breakers, etc.) May be selected by reference to the infrequent-faultincidence protection curve Infrequent-Fault Incidence Zone*

Category II or III Transformer Fault will be cleared by transformer primary-side protective device Optional main secondary –side protective device. May be selected by reference to the infrequent-faultincidence protection curve Fault will be cleared by transformer primary-side protective device or by optional main secondaryside protection device Feeder protective device

Frequent-Fault Incidence Zone*

Fault will be cleared by feeder protective device Feeders


Slide 48

Question What T/C Coordination interval should be maintained between relays?


Slide 49

Answer B t

A

CB Opening Time + Induction Disc Overtravel (0.1 sec) + Safety margin (0.2 sec w/o Inst. & 0.1 sec w/ Inst.)

I Copyright 2004 Operation Technology, Inc. – Workshop Notes: Protective Device Coordination

Slide 50

Question What is Class 10 and Class 20 Thermal OLR curves?


Slide 51

Answer • Class 10 for fast trip, 10 seconds or less • Class 20 for, 20 seconds or less • There is also a Class 30 for long trip time


Slide 52

Answer


Slide 53

08 - Device Coordination

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