FED-STD-228A
Method 6031.1
18 APRIL 2014
RESISTANCE, ELECTRICAL, INSULATION
1. SCOPE
1.1 This method is intended for use in determining the insulation resistance of insulated wire and cable.
The test should be conducted after the voltage withstand test, method 6111. The insulation resistance
test should be conducted under the supervision of the inspector in the plane of the manufacturer of the
wire and cable.
2. SPECIMEN
2.1 The specimen should consist of one or more coils or reels of finished insulated wire or cable or an
equal length of insulated wire or cable taken after the vulcanization process but before the braiding or
finishing operation.
3. APPARATUS
3.1 The apparatus shall be as follows:
3.1.1 A suitable container, equipped with stirrer, in which the specimen may be immersed in water.
3.1.2 A standard resistance, scale, and shunts of any suitable pattern.
3.1.3 A DC. voltage source preferably a battery of dry cells, that will supply a voltage of not less than that
specified in the detail specification or specification sheet.
3.1.4 A suitable instrument for measuring the resistance that will give an accuracy of within 10 percent
and a sensitivity of 1 percent of full scale deflection.
3.1.4.1 A galvanometer of fairly high sensitivity and having the following qualifications has been found to
meet the accuracy required. The galvanometer constant shall be not less than 50,000. The means for
indicating the deflection shall produce a sharply outlined indication on the scale, and the deflection shall
be not less than 100 divisions (measured from zero) when the variable shunt has been set to determine
the constant of the galvanometer. The resistance of the shunts and the calibrating resistor shall be
checked from time to time.
3.1.4.2 Any other suitable equipment arranged to apply a voltage of not less than that specified in the
detail specification or specification sheet.
3.1.5 Any apparatus that will measure the length of the specimen to an accuracy of 0.2 percent.
4. PROCEDURE
4.1 Unless otherwise specified in the detail specification or specification sheet, the insulation resistance
shall be determined on the same specimen used for determining the voltage withstand method 6111. It is
desirable that the test be conducted immediately following the voltage withstand test. In any case the
specimen shall be grounded and completely discharged before the measurement of insulation resistance
is made.
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