General Machine Products 70046 User Manual

Strand Tensionmeter
Operation and

GMP

Maintenance Manual

1

2

Table of

General 3

contents

General

Precautions 5
Calibration Chart 6
Temperature Compensation Charts 8
Dial 16
Using the Tensionmeter 16
Accessory Saddle 18
Re-calibration 19

An intensive study by the National Electric Safety
Code Clearances Subcommittee has resulted in a
completely new "Uniform System of Clearances"
adopted in the 1990 and subsequent editions of the
NESC. This revision places renewed emphasis on
utilities' practices for engineering and stringing of
aerial cables to maintain proper cable clearances
under the various specified conditions. The ability
to accurately measure strand tensions in the field is
essential for compliance with the code.

The GMP Strand Tensionmeter, also called a B
Strand Dynamometer, is a precision instrument de­signed to measure the tension of certain specific
zinc-coated guy wires and messenger cables per
ASTM A-475. The specific sizes and type(s) of
cable(s) with which this unit is compatible are
listed in the calibration chart which has been pre­pared for this specific serial numbered tension­meter and which bears that identical serial number.

3

The following list shows the various sizes, types
and designations of messenger cables for which
the tools can be calibrated:

Nominal Diameter
Inches mm Designation Description

1/4 6.35 6.6M 1 X 7 EHS

5/16 7.94 6M 1 X 7 Utility Grade

5/16 7.94 10M 1 X 7 EHS

3/8 9.52 10M 1 X 7 Utility Grade

7/16 11.11 16M 1 X 7 EHS

7/16 11.11 16M 1 X 7 Utility Grade

To obtain an accurate measurement it is imperative
that the strand to be measured be positively identi­fied as to its actual diameter and its grade, either
Utilities Grade or Extra-High Strength. Secondly,
the Strand Tensionmeter to be used must have a
current calibration chart with a corresponding se­rial number which has a calibration for the specific
strand you have identified.

The Tensionmeter measures the force required to
deflect the strand to an out-of-line position and
registers the amount of force required on the inte­gral dial. The actual strand tension is then deter­mined by referring to the calibration chart specifi­cally prepared for and furnished with each Ten­sionmeter, which converts the dial indicator read­ing into the actual tension value.

The instrument measures tension in pounds force
to within an accuracy of three percent (± 3%) or ±
150 pounds, whichever is greater.

4

The Tensionmeter is primarily made from nickel­plated steel and is furnished in a hard shell plastic
carrying case; the interior is cushioned with foam
for unit protection.

Each Tensionmeter has a registered serial number
stamped on the unit.

pPrecautions

• Do not measure tensions of 1/2" diameter

strand with the cable in place; these tension
values usually exceed 10,000 pounds.

• Do not drop or jar the Tensionmeter.

• Raise and lower the instrument with a hand

line.

• Keep the device away from dirt, grease, sand

or water.

• Keep foreign material from damaging the dial

or plunger.

• Maintain the unit in the carrying case when-

ever possible.

• Make certain that the correct calibration chart

is always kept in the carrying case.

• Use the Tensionmeter only on strand type and

sizes shown on the calibration chart.

• Do not use this device on strand tensioning

applications exceeding 10,000 pounds.

5

Calibration
Chart

Included with each Tensionmeter is a calibration
chart registered under the same serial number as
the Tensionmeter. This chart is to be used for in­terpreting the readings for that specific instrument
only.

No other chart should be used. No other type of
strand should be used.

The table across the top of the chart lists the com­monly used strand sizes for which the Tension­meter was calibrated, as well as the handle position
for each type of strand. The data in the chart indi­cates the dial reading of the Tensionmeter corre­sponding to the amount of strand tension in 100
pound increments for the normal tension range of
each strand size.

The chart indicates the date when the initial cali­bration was made. If the chart is lost, the Tension­meter must be returned for re-calibration.

Temperature
Compensation
Charts

Strand tension is affected by ambient temperature.
Generally speaking, strand tension increases as
temperature decreases due to the strand contraction
and, conversely, strand tension decreases as tem­perature rises, due to expansion. The Strand Ten­sionmeter will measure the actual tension at the
ambient temperature at the time of the measure­ment. You should consult with the Outside Plant
Facilities Engineer as to the proper strand tension
for the ambient temperature at the time of meas­urement.

6