Real Life Problems: TCI Solutions.
Arris Engineering Case Study--Wilkes Barre, PA

Arris Engineering Group, recently contracted TCI to help identify and solve a “phantom” elevator problem for a property management company. TCI analyzed the recorded data from a Drantez power-quality analyzer and was able to diagnose and solve the problem.

The Problem:
There are three primary elevators which serve the facility. Elevators 1 and 2 are served by a common feeder which is split into branch circuits to serve each elevator in the penthouse. Elevator 3 has a dedicated feeder. Each of these three elevators has been experiencing malfunctions which occur intermittently and without warning. This problem had persisted for number of years to the point where tenants threatened to leave if the problem was not corrected.

TCI’s Solution:
Since either the transients or the harmonics recorded could be responsible for the types of problems reported, TCI made two recommendations. As a first step, the data recorded at the isolation transformer clearly indicated that the installation of a quality surge suppressor on the secondary side of the transformer as well as on the input to the drive would be (see Section 7 for engineering specification). The recommendation is supported by IEEE Std 1100-1999 –design/installation practices (see Section 8, references.)

The second recommendation was to replace the existing isolation transformer with one that will treat both the harmonics and the notching (see Section 7 for engineering specification) created by the SCRs in the drive.