bs1361 40A

[moose man]

filling in schedual of test results today and one colume ask for max zs permited

but the one circuit as a bs1361 40A fuse on the circuit from the bus bar

and it does not state the value for that type of protective device

i know the formula is ZS = uoc dived Ia

circuit is running on 3 phase

cable is 6 mm

lenght is 10mtrs

tempeture is about 20deg

disconnetion time 0.4 sec

could any body help me get the value

thanks moose man

 

[moose man]

The make is bussman

and its a MD body type 2

moose man

 

[Chr!s]

For .4 disconnection id say 1.05 ohms

 

[moose man]

howdid you get that value did yu use the rms chart

moose man

 

[Chr!s]

howdid you get that value did yu use the rms chart

I used the time-current characteristic curve, the prospective current being (SYM. R.M.S. kA)

 

[septiclecky]

In 2007 certain types of fuses where reclassified and one of the was the BS1361 which is now a BS88-3

So all you need to do is look up the max Zs for a BS88 40A fuse in the regs

 

[speedster]

Hi, You mention the circuit is protected by a 40 A device.If you check the 17th edition,you'll find the disconnection time for a circuit exceeding 32A is 5 sec for TN systems ie TN-S and TN-C-S. As the protective device is a bs 3036 I would ring a manufacturer such as Wylex who manufactured this type of fuse to find the max Zs value.If the system is a TT, you will probably need a 100mA rcd in addition to the fuse,to protect this circuit (depends on the measured Zs,you need to measure this to ensure the circuit is earthed) ! Regards Speedster.

 

[moose man]

Hi, You mention the circuit is protected by a 40 A device.If you check the 17th edition,you'll find the disconnection time for a circuit exceeding 32A is 5 sec for TN systems ie TN-S and TN-C-S. As the protective device is a bs 3036 I would ring a manufacturer such as Wylex who manufactured this type of fuse to find the max Zs value.If the system is a TT, you will probably need a 100mA rcd in addition to the fuse,to protect this circuit (depends on the measured Zs,you need to measure this to ensure the circuit is earthed) ! Regards Speedster.

hi speedster measured zs is 0.17

 

[Chr!s]

Hello

In 2007 certain types of fuses where reclassified and one of the was the BS1361 which is now a BS88-3BS 1361 1971 was a testing standard along withBS EN 60269-3:1995, BS 88-3.1:1995,IEC 60269-3:198 all of which as you stated have been replaced by BS 88-3 Low-voltage fuses. Supplementary requirements for fuses for use by unskilled persons.

So all you need to do is look up the max Zs for a BS88 40A fuse in the regs

The regs only cover BS88 - 2.2 and BS88 - 6 which are different testing standards.

If the fuse is tested to 1361 then use that standard or the manufacturers information.

If the fuse is tested to BS88 (3) 1361 then again either use that standard or the manufactures information.

 

[kme]

Hi, You mention the circuit is protected by a 40 A device.If you check the 17th edition,you'll find the disconnection time for a circuit exceeding 32A is 5 sec for TN systems ie TN-S and TN-C-S. As the protective device is a bs 3036 I would ring a manufacturer such as Wylex who manufactured this type of fuse to find the max Zs value.If the system is a TT, you will probably need a 100mA rcd in addition to the fuse,to protect this circuit (depends on the measured Zs,you need to measure this to ensure the circuit is earthed) ! Regards Speedster.

No-one said anything about 3036, did they??

 

[speedster]

hi speedster measured zs is 0.17

S

Hi, I'm looking at page 49 BS7671 Table 41.4 ( BS 3036 fuses).

For 5 sec disconnection time, Max Zs for 30A fuse is 2.64 ohms,and Max Zs for 45A fuse is 1.59 ohms. The max Zs for a 40A fuse is somewhere between the two. Even allowing for temperature correction (Max Zs X 0.8) your measured Zs at 0.17 ohms will esily comply for a disconnection time of 5 Secs.

Please have a look yourself.

P.S. If you haven't done a City and Guilds 2391 course,I would recommend it. It's not easy,but well worth it !!

Best wishes, Speedster.

GuinnessGuinness

---------- AUTO MERGE Post added at 14:58 ---------- Previous post was at 14:47 ----------

hi speedster measured zs is 0.17

ax Tell me I'm a T**t !

Same page BS7671 same table ,but the row above BS3036 !!!****

BS 1361 the max Zs value for a 45A fuse is 0.96 ohms and for a 30A fuse is 1.84 ohms. You're still well below these figures with 0.17 !!!

Speedster.

P.S. haven't even had a Guinness Yet !!!

 

[moose man]

Hi

Speedster.

thanks for the replys i have done the 2392 & 2391 and past first time

you was right it wasnt very easy

the value i would look for is a Ib at 0,5s so then i could work out the zs useing ohm law which i would then put on the schedual of test results as max permited zs

 

[speedster]

HiSpeedster.

thanks for the replys i have done the 2392 & 2391 and past first time

you was right it wasnt very easy

the value i would look for is a Ib at 0,5s so then i could work out the zs useing ohm law which i would then put on the schedual of test results as max permited zs[/quoteS

Hi ,The max value of Zs should be taken from BS7671 (you might need to look at the 16th edition) or try ringing Wylex.They should know the figure you need.

Best wishes,

Speedster. Guinness

 

[moose man]

Got in touch with bussman tech dept and said max zs for a 1361

40A IS 2.2 ohms

and 140A for a .5 disconection time

he as e mailed a chart over so i can use it for future refrence

moose man

 

[Sidewinder]

mouse man,

How about an upload of the chart please?

 

[moose man]

Hi sidewinder

send me a pm and i will e mail it for you then if you dont mind you can up load it on to the forum as i am not sure how to do that yet

it might come usefull for sombody

thanks moose man

 

[speedster]

Job done !

Regards,

Speedster.

 

[Chr!s]

Got in touch with bussman tech dept and said max zs for a 1361 40A IS 2.2

and 140A for a .5 disconection time

Moose, i agree the chart shows 140 A for 5 sec disconnection, so 230/140 = 1.64 ohms

If you require .4 sec disconnection then 230/220A = 1.05 ohms