BS3871 MCB's

[Cremeegg]

Can anyone point me in the right direction for Zs values for circuits covered by these Type 1 MCB's. Specifically 6A, 16A and 32A. A link to time current curves would be good as well so I can see where Type 1,2,3 fit in with Types A B C D.

Thanks

 

[comms]

Zs values can be found in GN3 page 114
6amp
T1 = 8.00
T2= 4.57
T3= 3.20

16amp
3.00
1.71
1.20

20amp
2.40
1.37
0.96

30amp
1.60
0.86
0.64

32amp
1.50
0.86
0.60

I have a set of time graphs I will try to scan & post them.

 

[Adam_151]

Page 92 of the OSG for corrected figures

or page 51, tells you what multiplyer of the nominal current will garentee operation, also provides the lower band below which operation will not happen which is usful when checking discrimination, etc

 

[fireman22]

not sure where comms got his readings from i got (out of regs ) max zs for 0.4 & 5 sec.
6A 10ohm
16A 3.75 ohm
32A 1.88 ohm

 

[Cremeegg]

Many thanks - this is all rather embarrassing - I thought I'd go to the "bible" BS7671 and not look elsewhere as OSG seems wanting quite often. So I didn't think to look at OSG Table 2 - how many times have I used that for BS EN 60898 and BS EN 61009 figures and not noticed BS 3871 in the header. Similarly GN3 - ignored.

A lesson to us all - look at everything first then aska question.

Tail well between legs.