Engine Test Solutions with High Accuracy Transmitters

Engine tests require pressure transmitters which are compact but strong, have a high degree of precision, and can therefore be used to run rigorous tests on test cells. The models 422/423 pressure transmitters from Viatran are designed to provide a highly efficient solution for this application.

Features

Viatran models 422/423 have taken top place in this category for several reasons:

High Precision

The models 422/423 have piezoresistive sensors which have programmable electronic components designed for full compensation, which results in readings that have optional errors in accuracy as low as < ±.04%. This level of accuracy lends itself to rigorous excellence of testing by providing the best data on test cell performance. This kind of information in turn helps improve decisions that impact upon product design and conformity with industrial standards concerning how the proposed changes affect performance.

Compact Footprint

The small dimensions of the Viatran 422/423 allow for a greater number of sensors within the same unit area, providing for increased measurement density as well as for placing other measurement devices within the same test cell. These models are only 7/8 inch in diameter with a standard length of 3.78 inches.

Cost-effectiveness

Models 422/423 are designed with the utmost simplicity and clarity of purpose, keeping an eye to the target application. This enables the inclusion of only such features as are completely relevant to the test cell measurement, while those which are not essential for optimal function in such a setting have been pared away to bring the cost down while preserving a high standard of performance.

The Issue

Certain manufacturers of large engines have inquired regarding optional special features which could further boost the Viatran 422/423 model’s performance in their test cells. This request was made following an examination of the quality control (QC) report after test equipment calibration had been carried out. The report was the basis of an internal discussion as to how the procedure could be further streamlined without losing out on accuracy. The QC checks were carefully reviewed and one possible area of improvement was the capability of verifying whether the sensor electronics were actually functioning as specified even before the application of pressure on the units. The need for regular repetition of the recalibration process on the sensors was determined to be unnecessary as the sensor was almost always completely in accordance with the “as found” condition of the transducer provided the sensor or the system had passed the QC checks. Thus it was necessary to use a transmitter which allows shunt calibration as part of the system of electronics component scrutiny.

The Solution from Viatran

The Viatran models 422/423 can be upgraded using any of three shunt calibration options, as per the client requirement:

• Internal shunt calibration (Code DE) has a preset resistance of 80% of FSO on the bridge side once the user introduces a short circuit between the connector pins 5 and 6. Each unit has its value laser-etched on the housing of these models, for the purpose of accurate verification.
  
• Internal isolated calibration option (Code DA) is designed to isolate the shunt calibrator using an optoisolator chip. This is mounted on a separate PCB within the transmitter, which allows voltage to pass across it such that the shunt is activated at 80% of FSO. The advantage is that the isolation adds enhanced noise immunity to the shunt calibrator by keeping it separate from the sensor circuit.
  
• Externally powered optically isolated shunt calibrator (Code LV) is based on the use of an isolated shunt calibrator circuit which is activated by an externally applied voltage. The shunt cal value at which activation occurs is 80% of FSO. The circuit is isolated from ground loops which could produce noise.
  

The availability of several shunt calibration options adds to the versatility of the Viatran models 422/423 engine test pressure transducers.

This information has been sourced, reviewed and adapted from materials provided by Viatran.

For more information on this source, please visit Viatran.