Testing help

[James Sutton]

HI All

Have just installed a new circuit to supply power to a control panel.

Have tested it all came back fine if i need to carry out a ZE test how can this be done because cannot isolate the main board so cannot disconnect the Main CPC from the MET

Also have only carrird out a ZS at the furthest point of my installation which is the Switched Fused Spur

Should i do a ZS and PFC at the dis board or is at the spur fine

All results are recorded on schedule of test results the Red NIC forms. EXCEPT on the top left of the form where its asks for ZS AND PFC


Thanks just need a little guidance

James

 

[ezzzekiel]

ask dno for ze or use max value which they will prob give you anywayand it will result in a overall higher zs but as long as it is less than corrected Bs7671 values then your good to go

 

[James Sutton]

Took the Zs reading at the spur the furthest point on the circuit

@0.36 ohm

Will i need to take a Zs reading at the board and PFC

R1+R2 value was 0.14 ohm

and Insulation resistance @ 299M ohm

MCB is a D type

Thanks for ya help

James

 

[James Sutton]

I think the max Ze given will be 0.8 ohm for a TN-S system

 

[ezzzekiel]

your zs is taken at the furthest point - as you have done
pfc would prob be between l/n incoming (pscc) and l/ main earth(pefc) the higher being recorded.

unless you mean fault current for the circuit in which case its the same but taken from the circuits conductors ( i doubt this is what you require as most pfc readings taken from step 1 above.

and max ze will be 0.8 on tns or 0.35 on tncs

 

[SEC-Tom]

your zs is taken at the furthest point - as you have done
pfc would prob be between l/n incoming (pscc) and l/ main earth(pefc) the higher being recorded.

unless you mean fault current for the circuit in which case its the same but taken from the circuits conductors ( i doubt this is what you require as most pfc readings taken from step 1 above.

and max ze will be 0.8 on tns or 0.35 on tncs

On a 3-phase system is it correct that the PSCC is doubled?

Also could the Ze be worked out by Zs-(R1+R2)

 

[Sparky Ninja]

and Insulation resistance @ 299M ohm

Do you mean 299M ohms, or >299M ohms?

 

[Sparky Ninja]

Also could the Ze be worked out by Zs-(R1+R2)

What about the parallel paths?

 

[SEC-Tom]

What about the parallel paths?

Good point.

 

[ezzzekiel]

On a 3-phase system is it correct that the PSCC is doubled?

double a single phase value

 

[James Sutton]

>299M ohm using a megger 1552


Thanks lads for all ya help just abit un clear on a few things have to get everything spot on as this PDU supplies comms room racks/servers and theres no way i can turn this board off and if i were to trip anything i would have to walk the plank lol

Understand a little bit better have just passed my 2391 so still a getting used to it thanks for all ya help

Thanks James