Measurement report:
Elastic transformer bearings
Isotop® TR reduces floor vibrations
in a wide frequency range

1000 KVA transformer in the testing laboratory

Arrangement of the acceleration sensors

Description of the projectMeasurement setup

The extent to which the elastic bearing of transformers can contribute to a reduction in vibrations transmitted into the floor was investigated using structure-borne
noise measurements on a 1000 KVA transformer. The
measurements were taken in the testing laboratory of
Netzdienste Rhein-Main GmbH in Frankfurt. The transformer was placed on steel plates that were firmly embedded in the floor of a room with a basement underneath. The floor itself was constructed of reinforced
concrete.

On two opposite transformer feet, an acceleration
sensor was attached to the transformer bracket(above the elastic bearing) and another to the floor,
next to the transformer foot.
After the measurement was taken at rest, thevibrations that occurred were recorded while thetransformer was in idle mode.
To assess the effect of the elastic bearings, thefollowing installation situations of the transformer
were measured:— Without elastic bearing— On commercially available rubber bearings— On Isotop® TR from Getzner Werkstoffe

Commercially available rubber bearing

Key transformer data
— AC voltage: 50 Hz— Mass: 2450 kg— Power: 1000 kVA— Operating voltage: 6 kV, 3 phase

Isotop® TR

The spectrum of acceleration only shows significant vibration amplitudes (harmonic spectrum) at
multiples of the basic frequency of 100 Hz.
The measurements clearly showed that at frequencies of 200 Hz and 300 Hz, the commercially available rubber bearing examined caused a significant
increase in floor vibrations. On the other hand, withthe elastic Isotop® TR bearing, floor vibrations werereduced throughout the entire frequency range under consideration (graph 1).

Graph 1: Insertion loss in the frequency range
under consideration
Insertion loss in dB

Measurement results

302520151050-5-10-15

In the individual harmonics, an insertion loss of up
to 29 dB (1200 Hz) could be achieved. The effect ofIsotop® TR surpassed the rubber bearing by up to17 dB (400 Hz).

Graph 2: Insertion loss in comparison to arigid bearing
Insertion loss in dB

Compared with the effective value of the acceleration of the elastic bearings examined, Isotop® TRshows an improvement of 13 dB in comparison toa rigid bearing and of around 9 dB in comparison
with the rubber bearing (graph 2).

100 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400
Frequency in Hz
Rubber bearing
Getzner Isotop® TR

141210Improvement of 9 dB in
comparison to commerciallyavailable rubber bearings

86420Benefits— Measurable reduction in vibrations in theaudible frequency range and consequently
a reduction in secondary airborne noise— Significant reduction in floor vibrations— Easy and convenient installation— Durable and maintenance-free

AUSTRIA — Bürs GERMANY — Berlin — Munich — Stuttgart FRANCE — Lyon
JAPAN — Tokyo INDIA — Pune CHINA — Beijing USA — Charlotte

Rubber bearing

MB TPTR en © Copyright by Getzner Werkstoffe GmbH | 05-2020
Subject to change without notice.

Isotop® TR

JORDAN — Amman
www.getzner.com