View Full Version : LCR meter with overheat detectors (firewire)
johnsmith0774
14th Aug 2016, 11:50
Does anyone know why we use LCR meters on overheat and fire detectors (firewires) to measure the resistance instead of regular multimeters??
Thanks
tpng conehead
1st Sep 2016, 22:43
From memory, measuring impedance of firewire/detectors.
BCAR Section L
2nd Sep 2016, 17:04
that must be a candidate for answer of the year!
LCR meter/impedance you are a real genius aren't you.
The question however was why?
tpng conehead
3rd Sep 2016, 10:31
AC powered system.
tpng conehead
3rd Sep 2016, 22:11
Multimeter measures the DC resistance.
LCR meter is used as the firewire/detector has an AC sensing voltage, hence need to measure the impedance.
BCAR Section L
4th Sep 2016, 06:58
the question remains.....why?
A bog-standard multimeter measures resistance by applying a voltage and measuring a current. An LCR bridge measures impedance with zero current. Measuring under null conditions is more accurate, but also passing a current through a firewire is not the best way of promoting its general health and longevity.
PDR