Applications

Thermal techniques can be applied where temperature, pressure or flows are critical factors requiring routine monitoring or where changes in values of these parameters indicate possible reductions in performance efficiency. Examples are:

Boiler flue gas - temperature, pressure
Water & steam - temperature, pressure, flow
Air - temperature, pressure, flow
Bearings - temperature
Filters - pressure, flow
Heat exchangers - temperature, pressure, flow
Pumps - flow, pressure
Switch gear - temperature

Transforms - temperature

Thermal Monitoring

Thermal monitoring is important for components which generate, transfer or store energy as heat. Typical items that are monitored are:

·	Thermal installation

·	Bearing Housings

·	Coolant/lubricant

·	Heat exchangers

·	Electrical wiring housings

·	Fuse boxes

·	Circuit Boards

·	Transforms

Motors

And any temperature rises may be caused by

Damaged / perished thermal and electrical insulation
Incorrect electrical loading
Friction due to rubbing components

Thermocouples & RTD

The NetPod 4000 uses contact sensors to measure temperature at specific locations and requires the sensor to be placed within the surface of the component to be assessed. The results achieved are instant and very accurate and can be used for the basis of automatic alarm systems and in depth analysis operations.

Solid State Isolated Thermocouple Multiplexer

The NPMUX-8AI shown below is an 8 channel solid state isolated analogue multiplexer unit for the NetPod 4000 series instrumentation. The use of solid state multiplexer techology ensures the highest possible reliability and low noise operations.

Description

The multiplexer unit contains 8 analogue differential input channels and connects directly to a type J or K thermocouple interface of the NetPod instrumentation.

Channel selection is carried out via the digital control signals made available to the multiplexer card from the instrument via the digital I/O lines. Each analogue interface card within NetPod, be it a 24 bit high speed or low resolution 16 bit can be connected directly to the output channel of the multiplexer cards.

The multiplexer card is used to expand the number of sensor inputs that can be connected to a NetPod 4000 instrument making them far more cost effective. The multiplexer also offers a high level of individual channel isolation and enables high common mode signals to be applied. Even though thermocouple signals are only small, in the region of 50 mV at best, they can be obtained from sensors connected to machinery operating at a higher chassis level than the common earth.

The high common mode operating capability of the multiplexer enables the unit to accept signals without any special considerations from sensors mounted anywhere on plant machinery without any additional interfacing.

On plant it is possible to get local earth potentials at different levels when connecting sensors to plant or structures which are located some distances from each other. The NetPod 4000 instruments use of isolated inputs enables these types of signals to be used without affecting readings accuracy.

The solid state nature of the Multiplexer cards ensures that high reliable operations for many years without any fear of mechanical breakdown. In case of accidental overload the multiplexer cards will prevent the 4000 series instruments from any damage.

Part Number: NPMUX-08