Specifications

90
Multimeter/Continuity test
Continuity testers are simple devices designed to verify a complete electrical path through
an object or circuit. They are especially useful for checking fuses of all types, light-bulbs, and
wire paths.
This tester is usually comprised of:
1. Two leads
2. A small body where the leads meet and contain...
3. Some form of indicator
A number of devices are manufactured to assist consumers in testing electrical continuity,
ranging from multimeters as shown in Fig.7.2, which have a wide range of additional applications,
to simple electrical continuity testers that light up if electrical continuity is present. These devices
use two electrical probes, which form a complete circuit when touched together. Consumers
can test the device to ensure that it is working properly by turning it on and touching the probes
together – the meter should read zero, or the indicator light should turn on, indicating a closed
circuit. When the probes are not touching anything, the metered device will read infinity, showing
that the circuit is open.
Fig. 7.2a – Analog Multimeter
Open circuit test and Short circuit test: Multimeter can be used for this test. For this,
multimeter should be set in resistance mode of measurement. To check the existence of any
open circuit or short circuit between any two points in the wiring circuit, the electrical supply to
the circuit should be switched off first. Then put the multimeter probes between the two testing
points in the circuit. If multimeter reads ‘¥’ ohm, it indicates open circuit. If multimeter reads ‘0’
ohm, it indicates short circuit. This is shown in Fig.7.3 and 7.4.
7.4 INSULATION TESTING :
This testing is important, as insufficient insulating can result in leaking current. Leaking current
creates heat, which can cause a fire. The current can seep out and flow into another pathway,
Fig. 7.2b – Digital multimeter