Relay Setting Coordination

RELAY COORDINATION BETWEEN INCOMER & OUTGOING FEEDERS OF MV SWITCHGEAR

I/C

CTR 2500/1

CTR 700/1

a

4500KW

A

CTR 250/1

b

2500KVA

B

C

CTR 2500/1

c

D

CTR 1250/1

d

2500 A

1250 A

I]

I

Between Incomer and Motor Feeder FAULT TYPE: SHORT CIRCUIT Motor Rating Motor rated voltage Motor full load current CT Ratio (CTR) CT Secondary current

4500 KW 6.6 KV 454.2 700/1 0.65

Calculation of Operating time of over current protection of Motor Feeder Current Setting in % (PS) Current Setting (I>) (CTR X PS) Fault Current considered (Amps) (I)

2.0 1400.00 25000

Operating time calculated as follows

𝑡 𝑆 =

𝐴

𝐼 𝑐 −1 𝐼>

Selected Characteristic Time/current curve group Very inverse C K (TMS)

+𝐵 K

𝑇𝑀𝑆

𝐼 𝛼 −1 𝐼>

K

IEC Very inverse α (A) β (B) 13.5 0

Operating time of Over current protection,t (sec) II

𝑡 𝑆 =

Calculation of required TMS for Incomer Feeder Fault current considered (A) Current Setting in % (PS) Current Setting (I>)

1 0.7

0.5606 25000 100% 2500

0

Operating time calculated as follows

𝑡 𝑆 =

𝐴

𝐼 𝑐 −1 𝐼>

Selected Characteristic Time/current curve group Very inverse C K (TMS)

+𝐵 K

𝑡 𝑆 =

K

1 0.92

1.38

Minimum TMS for discrimination Selected TMS considering that TIE between unit boards are closed

I

𝐼 𝛼 −1 𝐼>

IEC Very inverse α (A) β (B) 13.5 0

Operating time of Over current protection,t (sec)

I]

𝑇𝑀𝑆

Between Incomer and Transformer Feeder FAULT TYPE: SHORT CIRCUIT Transformer Rating Transformer rated voltage Transformer full load current CT Ratio (CTR) CT Secondary current

Calculation of Operating time of over current protection of Transformer Feeder Current Setting in % (PS) Current Setting (I>) (CTR X PS) Fault Current considered (Amps) (I) Operating time calculated as follows

0.529 0.92

2500KVA 6.6 KV / 433V 218.69 250/1 0.87

0.9 225.00 25000

#REF!

𝑡 𝑆 =

𝐴

𝐼 𝑐 −1 𝐼>

Selected Characteristic Time/current curve group Very inverse C K (TMS)

+𝐵 K

𝑇𝑀𝑆

𝐼 𝛼 −1 𝐼>

K

IEC Very inverse α (A) β (B) 13.5 0 1 1

Operating time of Over current protection,t (sec) II

𝑡 𝑆 =

0.1226

Calculation of required TMS for Incomer Feeder Fault current considered (A) Current Setting in % (PS) Current Setting (I>)

25000 100% 2500

Operating time calculated as follows

𝑡 𝑆 =

𝐴

𝐼 𝑐 −1 𝐼>

Selected Characteristic Time/current curve group Very inverse C K (TMS)

+𝐵 K

𝑡 𝑆 =

𝑇𝑀𝑆

𝐼 𝛼 −1 𝐼>

K

IEC Very inverse α (A) β (B) 13.5 0

Operating time of Over current protection,t (sec)

Minimum TMS for discrimination Selected TMS considering that TIE between unit boards are closed

1 1

1.5 0.529 0.92

0

CHGEAR

RELAY COORDINATION BETWEEN INCOMER & OUTGOING FEEDERS OF LV SWICHGEAR

I/C-2

I/C-1

CTR 4000/1

CTR 4000/1

CTR 4000/1

B/C

B

A CTR 400/1

CTR 400/1

a

b

a

180/200 KW

180/200 KW