T272中文资料雷迪数据手册PDF规格书

Features / key benefits

l The T272 high resistance cable fault locator has been

designed to meet the requirements of engineers in

locating cable faults in the resistance range from zero to

200 megohms. Faults can be between two conductors,

or between a conductor and its metallic sheath,

concentric neutral or earth.

l Easy to operate, the T272 features solid state circuitry

and utilises a conventional Wheatstone Bridge circuit in

which the two sections of the faulty conductor, one on

each side of the fault, together with a good conductor

if necessary, comprise the two external arms of the

bridge. The other two arms of the bridge are contained

within the instrument.

l By employing a detection circuit of extremely high

input resistance it is possible to locate high resistance

faults without the loss of sensitivity associated with

other types of low and high voltage bridges. A ten turn

vernier balancing control is provided which indicates the

fault position as a percentage of the total loop length.

If both ends of the faulty conductor are not accessible

at the test end then a good conductor of the same

crosssectional area is required. If the good conductor is

of a different size then a conversion factor may be used

to calculate an equivalent loop length. Alternatively, a

pair of conductors from an auxiliary cable may be used

or, if the cable length is not too great, an overland lead

can be run out to enable the bridge test to be carried out.

l With this bridge arrangement, faults having resistances

up to 200 megohms in dielectrics such as rubber and

polyethylene can be located with an accuracy well

within ± 0.5 of the loop length and typically 0.1,

although this may be limited by the nonuniformity of the

conductor.

l The T272 is contained within a fibreglass housing fitted

with a carrying strap. All terminals, controls and null

detector microammeter are mounted on the top panel.

l Complementary to Bicotest TDRs for locating high

insulation resistance faults.