Interface box
The Nortek interface box is designed to be use with long cables. It has several features that are of great importance for the long term operation of online systems
The main function of the interface box is to provide power to the instrument and transfer data using the RS422 protocol. It can be powered using AC or DC input and it is possible to communicate with the instrument using a USB or RS232 connection to the computer. The DC input can be used to achieve an UPS (Uninterruptible Power Supply) function by connecting an external battery. The external battery voltage (for example, a car battery) should be kept below 14V. Note that the interface box will not charge this battery.
| Interface box, electrical specification | Value |
| AC input voltage range | 100-240VAC, 50-60Hz |
| DC input voltage range | 10-18VDC |
| Maximum power drawn from either AC or DC input | 30W |
| Output voltage | 48VDC |
| Maximum output current | 400mA |
| Output short circuit protection. | Hiccup mode |
| Maximum time from cable break in water to output power off. | 3s |
| Startup procedure after cable break. | Turn input power off / on |
The interface box comes in two versions, a 48 VDC system that is used for cabled online systems and a 18VDC version that has already been in use for some time with Nortek Vessel Mounted Current Profilers.
DCDC converter in instrument
In the instrument, a DCDC converter is used to downconvert the supply voltage to 15 V. The DCDC converter comes in two versions, one for the AWAC and one for the Aquadopp/Aquadopp profiler/Vector. Here are some of the key techncial elements for the DCDC converter:
|
Electrical Characteristics |
Value | Conditions |
| Operating input voltage | 21-54VDC | Cable impedance < 1ohm |
| Peak current operation | 320mA | Max during operation and power up |
| Switching frequency | 350kHz | Typical |
| Output voltage | 15VDC | +-5% |
| Output current, continuous | 0,5A | Vin 48V, 1m Cable, |
| Output current peak pulse | 4,5A | 100ms, 2Hz, Vin 48V, 1m Cable |
| Output voltage drop during peak pulse | 640mV | 4,5A, 100ms, 2Hz, Vin 48V, 1m Cable |
| Startup time | 1,5sek | Typical |
| Off time if overloaded | 1,3sek | Typical |
