Main Instrumentation
Earth Point

Transient Protection
Varistors

Mains Isolator
Switch

Fig 6

Instrumentation Earth Point

The instrumentation has a central earth point and the external earth must be connected here. It is not recommended to use the system without the earth being connected. The Earth point utilises the industry standard Green/Yellow DIN Earth Tag.

Instrumentation Must Have An External Earth Connection.

Transient Protection

The transient protection module fitted into the instrumentation protects against spikes in the mains power supply and lightening strikes to the mains input cables.

The transient protection is provided by a varistor module supplying protection across the Live - Neutral and Neutral - Earth mains connections. A transient will cause the main input fuse, see Fig X to fail.

Mains Isolator Switch

The mains isolator switch power on and off mains supply to the instrumentation and isolates both the Live and Neutral mains inputs.

Wiring Schematic & Component Layout

Current Loop Interface

Level Sensor Power

The acoustic level sensor uses a powered current loop to obtain power and and pass signal information to the logger. As shown in Figure 7 the height signal in the form of the current loop is converted into voltage across the sense resistor before being recorded by the logger.

The 24V Power supply and the 0V Ref on the logger unit complete the current loop.

Fig 7

Pin-outs looking into logger Input

Figure 8 - General System Wiring Schematic

Sensor Deployment

The acoustic sensor can be deployed up to 3 Km away from the logger unit when using a 4-20 mA current loop to pass signals to the logger for recording purposes.

The acoustic sensor should be deployed approximately 1 m from any supporting walls to prevent false readings

3° max

0.88 m

D

D Min = 0.3 m
D Max = 8 m

To Logger

Fig 9

Fig 10