Fuse Characteristics

[Derm]

Hi folks,
This has probably come up before in one way or another but anyway....what do the letters describing fuse types mean? e.g. gL gG gR gH and aM ?
I'm looking to specify a fuse on the secondary side of a VT for high accuracy metering purposes. The meter is 0.2% and VT cores are CL0.2s. Average run of approx. 100 meters of 4x6mm NYCY cable from each VT to the meter in the control room. Having gone to this trouble and needing a low enough fuse to protect the meter (2A max) I can't afford to drop volts on the fuse which is protecting the meter.
Does anyone have any experience/thoughts on the above?


Stay safe!

 

[busbar]

Typical burden for modern electronic meters should make concern for voltage drop across PT-secondary fuses inconsequential. More likely—is meter auxiliary power served from the same PTs?

 

[jbartos]

Suggestion: Visit

http://www.thefusecompany.co.uk/shop/default.php?cPath=28

etc. for fuse categories

 

[jbartos]

Suggestion to Derm (Electrical) Dec 16, 2003 marked ///\\This has probably come up before in one way or another but anyway....what do the letters describing fuse types mean? e.g. gL gG gR gH and aM ?
///Please, see my posted link above\\I'm looking to specify a fuse on the secondary side of a VT for high accuracy metering purposes. The meter is 0.2% and VT cores are CL0.2s. Average run of approx. 100 meters of 4x6mm NYCY cable from each VT to the meter in the control room. Having gone to this trouble and needing a low enough fuse to protect the meter (2A max) I can't afford to drop volts on the fuse which is protecting the meter.
Does anyone have any experience/thoughts on the above?
///The fuse specifications are too restrictive. Small fuse rating increases a voltage drop across the fuse, and fuse resistance or impedance. Therefore, the meter may be specified with internal fuse, and the upstream fuse may just protect the 6mm conductor or cable.\\\

 

[Derm]

Thanks for the reply jbartos. The meters aux power will come from the same vt supply, thanks for reminding me!.
The internal fuses at the meter were orginally planned to be 2A for protection of the meter (& aux supply) but these cartridge type were found to drop too many volts (2A fuses too high impedance) so these were changed for 32A of the same make which did not give any loss, and could be done without any cost - changing the holder would cost!.
The upstream fuse near the VT's will now have to protect the cable & the meters!

 

[Derm]

sorry Busbar..it was yourself who reminded me if the aux supply.
I forgot to add the upstream fuses are planned to be D type DIAZED.
However if a suitably low impedance fuse cannot be got then we'll just have to replace them with a bigger rating and forgo the protection aspect!