R
1T
R
N
R
3
R
2
R
1
1
......
1 1
1
=
+ + +
+
T
N
R
RRR
R
2
31
2
1
......
11
1
=
+++
+
NT
N
N
R
RRR
R =
+++
+
- )1(21
1
......
11
1
32 33
great errors.
Owing to the same reason, we neglect the impact of mutual resistance and
calculate the equivalent resistance of ground resistance in parallel from the
general meaning. Thus, for ground system of N N is small, but bigger than 2
ground bodies, we can list out N formula:
Of which, R1 R2 .RN is the ground resistance of N ground bodies we need
to solve.
R1T R2T RNT are respectively the resistance measured on each ground
branch circuit by clamp meter.
This is nonlinear equations with N unknown and N equations. It has certain
solution, but which is difficult to solve by manual operations and even impossible
when N is quite big.
Purchasing the limited point ground system calculating program software from
our company, user shall be able to solve it by using an of fice computer or laptop.
Principally, except for the neglect of mutual resistance, the method would not
result in any measurement error brought by neglecting R0.
Users need to pay attention that: the number of connected ground bodies in your
ground system shall be exactly equal to that of measurement value for program
calculation and the program shall output the same number of ground resistance
value.
3 Single Point Ground System
From the test principle, UNIT series clamp meter can only be used to measure
loop resistance but the single point ground. However , user can make a loop to
test by using a test line and ground polarity near the ground system. Two methods
of measuring single point ground by clamp meter are introduce in the following
and the method could be applicable to occasions that traditional voltage-current
UT276A/278A OPERATING MANUALUT276A/278A OPERATING MANUAL
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