FAA L830 Transformer Qualification

4.1 Equipment Qualification Procedure. Procedures for obtaining equipment
qualification approval are now contained in AC 150/5345-l (latest edition),
Approved Airport Lighting Equipment.

4.2 Tests. The following tests shall be conducted on three random samples
to prove compliance with this specification. Unless otherwise specified,
all tests shall be made at room temperature (approximately 25° C. ± 5° C.),
using a suitable sine wave power source with primary current maintained at the
specified values by means of an auto-transformer. If it is necessary for water
bath temperature to be substantially different from limits set above, the
proper temperature coefficient for the compound being used may be applied
when computing insulation resistance values. It will be the manufacturer’s
responsibility to furnish proof that the coefficient used is correct.

Proof shall be in the form of a certified test report furnished by the
manufacturer . Joints between transformer leads, and between transformer
leads and test leads, will not be taped during any of the dielectric or
insulation resistance tests required by paragraphs 4.2.3 and 4.3.2 herein.
All test lead connectors shall be checked with a "go," "no go" prior to use
to assure proper watertight seal.

4.2.l Characteristics Test. The samples shall be tested to show that their
electrical characteristics are as specified in Table 1. All corrections
necessary to compensate for meter-power consumption shall be applied. The
transformers shall be operated in air at room temperature with rated load
connected to the secondary until the transformer windings have reached
normal operating temperature at which time the measurements will be taken.

4.2.2 Shock Test. The sample transformers shall be dropped twice from a
height of 6 feet (2 meters) on a smooth hardware floor; once so they hit on
a bottom corner or location where the most damage is likely to occur due to
the core cutting into the case, and once so they hit on a side or location
where the most damage is likely to occur to the windings. Lead rigidity
shall be tested by securing (just below the connector) each lead one at a
time, in a clamp fastened to a support, elevated a distance in excess of the
length of leads and then releasing the transformers for a free fall from the
clamp elevation. The lead clamp used shall be such as to not cause damage
to the lead at the point of attachment. After the completion of these
tests, the transformers shall be tested to insure that they meet the secondary
current requirements at rated load. A change of more than one percent from
the results obtained in the test specified in paragraph 4.2.1 or evidence of
damage to the case and attaching leads shall be cause for rejection.

4.2.3 Insulation Resistance. The sample transformers shall be subjected to
a continuous 20-cycle test as follows:

4.2.3.1 Mating Connectors. Mating connectors that were gauged with "go" and
"no go" gauges shall be installed in the three connectors of the transformers.
The mating connectors shall not be removed before completion of the 20-cycle
testing. If they are removed for any reason, tests shall be repeated so that
the transformers and their connectors satisfactorily pass 20 continuous
cycles. One cycle shall consist of the sequence of operation specified in
paragraphs 4.2.3.2, 4.2.3.3, and 4.2.3.4.

4.2.3.2 Transformer. The transformers shall be operated, with mating
connectors installed, for a minimum of 6 hours in air at room temperature
with rated current flowing in primary coils. The secondaries of the
transformers shall be open-circuited. The procedure of this paragraph shall
hereinafter be referred to as "the heating cycle."

4.2.3.3 Water Immersion Test. Immediately following the heating cycle,the
transformers, with leads and connectors, shall be completely submerged in
water, which is grounded, at room temperature. Care should be taken to
insure that all molded connections, on transformer leads and test harness,
are completely immersed in water during this test. Immediately after
immersion, the insulation resistance of each coil and lead assembly shall be
measured. The time period between interruption of the heating cycle and
start of the measurement shall not exceed 3 minutes.

4.2.3.4 Soaking. The transformers and their connectors shall be soaked in
water, at room temperature, for not less than 12 hours, and the insulation
resistance measurements repeated.

4.2.3.5 Resistance Measurements. Measurements of dielectric and insulation
resistance shall be made with direct current. The test voltage shall be
applied for 1 minute between each coil and ground with the other coil
grounded and its connectors submerged in water. The insulation resistance
at the test voltage indicated shall equal or exceed the minimum values
specified in Table 2. Zero and maximum readings of the test instrument
shall be periodically checked by touching the high voltage lead to the
water surface and suspending it in air. After instrument needle settles
down following current inrush, it shall remain steady without fluctuations.