METROSILS FOR HIGH IMPEDANCE RELAYS
In some applications of high
impedance relays a non-linear
Metrosil resistor is required to
limit the current transformer
secondary voltage to a safe
level during maximum internal
fault condition. The Metrosil
chosen depends on the relay
setting voltage and the
maximum secondary internal
fault current.
Relays attached to Current
Transformers with 1A rated
Secondary Output.
Single disc Metrosils are suitable
for secondary internal fault currents
up to 50A rms. For larger fault
currents refer to Metrosils for relays
on 5A CTs.
Table 1 Identification of Metrosils for Relays on 1A CTs.
Single element or three element Metrosils are provided for use with single and triple pole relays respectively.
Maximum Relay Setting Voltage NomCin al Characteà r istic Single Pole Relay Triple Pole Relay
125V rms
175V rms
185V rms
450 0.25 600-A/ S1/ 256 600-A/ S3/ I/ 802
300V rms
325V rms
900 0.25 600-A/ S1/ 1088 600-A/ S3/ I/ 1195
400V rms 1100 0.25 600-A/ S1/ 6315 600-A/ S3/ I/ 6324
V = CI Ã For dc or instantaneous values.
Ã
C
Irms Vrms
1
2 52 . 0 Ÿ
Ÿ
ž
Å Å Â
âº
= For applied sinusoidal voltages.
Vpeak = 1.09C( Irms) Ã For applied sinusoidal currents.
Table 2 Leakage current, protection voltage and short time currents.
Short Time Current Rating
Metrosil
Identification
Maximum
Relay
Setting
Voltage
Maximum
Metrosi l
Leakage
Current at max.
Relay Setting
Voltage
Maximum
Protection
Voltage at
the peak of
50A rms 1 sec. 2 sec. 3 sec.
Maximum
Continuous
Voltage
Rating
125V rms 19 mA rms 1435V pk
600-A/ S1/ 256 175V rms 73 mA rms 1435V pk
185V rms 90 mA rms 1435V pk
45A rms 30A rms 22A rms 200V rms
300V rms 30 mA rms 2870V pk
600-A/ S1/ 1088
325V rms 50 mA rms 2870V pk
39A rms 30A rms 17A rms 350V rms
600-A/ S1/ 6315 400V rms 55 mA rms 3500V pk * 46A rms 26A rms 19A rms 425V rms
* 600A-A/ S1/ 6315 will hold to 3400V pk at peak of 46A rms and 3000V pk at peak of 30A rms.
Relays attached to
Current Transformers
with 5A rated Secondary
Output.
The Metrosil chosen depends on
the relay setting voltage and the
maximum secondary internal fault
current. Single disc Metrosils are
suitable for secondary internal fault
currents up to 50A rms. Metrosils
with multiple discs connected in
parallel are used for larger fault
currents.
Table 3 Identification of Metrosils for Relays on 5 A CTs.
Max. Internal Max. Relay Setting Voltage
Secondary Fault
Current 200V rms 250V rms 275V rms 300V rms
50A rms 600A/ S1/ 1213
C = 540/ 640
600A/ S1/ 1214
C = 670/ 800
600A/ S1/ 1214
C = 670/ 800
600A/ S1/ 1223
C = 740/ 800
100A rms 600A/ S2/ P/ 1217
C = 470/ 540
600A/ S2/ P/ 1215
C = 570/ 670
600A/ S2/ P/ 1215
C = 570/ 670
600A/ S2/ P/ 1196
C = 620/ 740
150A rms 600A/ S3/ P/ 1219
C = 430/ 500
600A/ S3/ P/ 1220
C = 520/ 620
600A/ S3/ P/ 1221
C = 570/ 670
600A/ S3/ P/ 1222
C = 620/ 740
Table 4. Leakage current, protection voltage and short time currents.
Metrosil Short Time Current Rating
Identification
Maximum
Relay
Setting
Voltage
Maximum
Metrosil Leakage
Current at max.
Relay Setting
Voltage
Maximum
Protection
Voltage at the
peak of Fault
Current 1 sec. 2 sec. 3 sec.
Maximum
Continuous
Voltage
Rating
600-A/ S1/ 1213 200V rms 35 mA rms 1730V pk 50A rms 30A rms 20A rms 220V rms
250V rms 40 mA rms
600A/ S1/ 1214
275V rms 50 mA rms
2120V pk 50A rms 25A rms 18A rms 290V rms
600-A/ S1/ 1223 300V rms 50mA rms 2400V pk 40A rms 20A rms 15A rms 330V rms
600-A/ S2/ P/ 1217 200V rms 70mA rms 1730V pk 100A rms 60A rms 45A rms 230V rms
250V rms 75mA rms
600-A/ S2/ P/ 1215
275V rms 100mA rms
2120V pk 90A rms 50A rms 35A rms 290V rms
600-A/ S2/ P/ 1196 300V rms 100mA rms 2400V pk 80A rms 45A rms 30A rms 330V rms
600-A/ S3/ P1219 200V rms 100mA rms 1730V pk 150A rms 85A rms 60A rms 220V rms
600-A/ S3/ P/ 1220 250V rms 100mA rms 2120V pk 135A rms 75A rms 55A rms 265V rms
600-A/ S3/ P/ 1221 275V rms 100mA rms 2200V pk 125A rms 70A rms 50A rms 290V rms
600-A/ S3/ P/ 1222 300V rms 100mA rms 2600V pk 115A rms 65A rms 40A rms 330V rms |
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