4.Maintenance

All GeoNet devices are designed to operate in field environments with minimal upkeep; nevertheless, there are some basic maintenance procedures that should be followed to ensure maximum reliability and functionality.

4.1Preventing Water from Entering the Enclosures

GeoNet devices are designed to be splash proof and rain proof, but are not submersible.

These units are sealed by a gasket preventing water entry, so long as the screws that hold the lid in place are properly tightened and the gasket inside the lid is properly aligned. It is also very important to ensure that all the cable fittings are securely tightened. Models that feature a 10-pin connector are equipped with a watertight cap, which must be installed when the connector is not in use.

Despite these precautions, the loggers may encounter leakage along the cable if the cable is cut, or if the unit is installed in an especially humid environment. In this type of environment, geokon recommends that the internal desiccant packs be replaced at intervals to prevent condensation from corroding or shorting out the internal electronics.

4.2Battery Life

Battery life is affected by the quantity and physical configuration of the loggers, along with weather conditions and the radio environment (as related to retries).

Loggers that are the only communication link between other loggers and the gateway will have a shorter battery life than those that have no routing responsibility.

Table 9 below shows an estimate of battery life in a network of fewer than 20 loggers based on the number of readings collected and forwarded to the gateway. More than 1,000 days of battery life are possible when using a scan rate of one hour or higher, with only one hop. A more frequent scan rate will reduce this estimate. If greater battery life is needed, a 12-volt nominal input is available from geokon.

table 9: Battery Life Estimates

4.3Replacing Batteries

The network must be put into deployment mode prior to replacing the batteries in the gateway. This is also best practice when replacing batteries in loggers.

Replace D cell batteries when their measured voltage drops below 2.0 VDC. Replace external 12-volt batteries when the measured voltage drops below 11 VDC.

All data is retained in nonvolatile flash memory. Data will not be lost even if the batteries are removed for an extended period (e.g., years).

Replace the batteries as follows:

1.Place the network in deployment mode by pressing the status button on the gateway. Within six minutes the green LED will begin flashing every 10 seconds.

2.Open the logger by unscrewing the four captive screws on the front of the enclosure. Make sure that no dirt, water or other contaminants are allowed to enter the enclosure.

3.Set the battery select switch to the OFF (middle) position.

4.Remove the existing batteries, if installed.

5.Install the batteries by aligning the positive (+) side of the D cells with the
(+) indicator in the battery holder. Push the batteries straight down into the holder.

6.For Move the battery select switch to either the Alkaline or Lithium position depending on the type of battery being used. An LED will flash on the right side of the box indicating the unit has power. Once the logger reconnects to the network, the green LED will blink every 10 seconds in unison with the LED on the gateway.

Note: If replacing the batteries in a network gateway and power is restored promptly, the gateway will remain active. If power is not restored promptly the network time will be lost and must be reset using the Agent software. The loggers within the network will reconnect automatically.

4.4Lightning Protection

Each vibrating wire (VW) channel is protected by a 230V gas discharge tube, followed by a high-speed surge protector and a transient voltage suppression diode. Each thermistor (TH) channel is protected by a 230V gas discharge tube, followed by an inductor (lower resistance than high-speed surge protectors) and a transient voltage suppression diode.

For these components to safely divert lightning energy to ground, a solid electrical connection to earth ground is required. A copper grounding rod at least six feet in length should be driven into the soil to a minimum depth of three feet, as close to the device as possible. Alternatively, any other suitable earth ground attachment may be used. Connect the grounding rod to the copper grounding lug on the exterior of the device (if equipped) with a 12 AWG or larger wire. This will provide a path from the device to earth ground in the event of a lightning strike.