Related Manuals for NorthStar NT11
Summary of Contents for NorthStar NT11
- Page 1 Operations Manual Model NT11 & NT11-E June 18 2002 3609 North 44 Street Phoenix, AZ 85018-6023 Internet: www.northstarcontrols.com Fax: (941) 426-0807 Tel: (941) 426-6396...
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Page 2: Manual Contents
Manual Contents Glossary Page 1 Description Page 2 Characteristics Page 2 Installation Page 3 Adjustments Page 4 Connections Page 6 Theory of Operation Page 6 Block Diagram Page 7 Detailed Description of Operation Page 7 Parts List Page 9 Schematic Page 10 Glossary d.c. - Page 3 The fault type sequence is one flash and one space is for an open, two flashes and one space is for a short and three flashes and a space indicate a greater than 25% inductance change. The NT11 and NT11-E are fail-safe detectors so in fault they will provide a constant output until the fault is cleared.
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Page 4: Installation
• Outputs: Relay or Optically isolated Solid State. Solid State output rating maximum voltage 47V, ON voltage <1.5V at 50ma. Relay output rating 10A, 277VAC, 24VDC. Output is fail-safe (assumes detect condition on power failure). • Power: 115VAC +/- 20%,1W. •... - Page 5 • Observe the detection of vehicles by watching the front panel detect LED. Loop installation: The Northstar NT11 and NT11-E detectors will operate with loop and lead-in’s whose total inductance is between 20µH and 2000µH. Loops with a perimeter less than 30 feet should have at least three turns, between 30 feet and 120 feet should have two turns and over 120 feet should have one turn of wire.
- Page 6 Adjustments Continued – NT11 and NT11-E F0F0 = Low F1F0 = Med Low F2F0 = Med High F1F2 = High Setting 0 = 2.56% Setting 1 = 1.28% Setting 2 = .96% Setting 3 = .64% Setting 4 = .48% Setting 5 = .32%...
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Page 7: Theory Of Operation
Theory of Operation Systems Description The Northstar Controls NT11 and NT11-E sensor unit consists of the following major circuit elements: The loop oscillator, the digital period measurement circuit, the microcontroller, the front panel switches and indicators and the output circuits... - Page 8 Block Diagram of NT11/NT11-E Loop Sensor Unit Indicators Frequency Measuring Circuit Loop Switches Loop Oscillator Microcontroller Switches Output Indicators Detailed Description of Operation When power is applied to the sensor unit, the microcontroller first checks the condition of the front panel switches to determine that the channel is enabled, what sensitivity level is set and what operational mode is required.
- Page 9 Frequency modification switches at the front panel allow the oscillator frequency to be modified when multiple loops and multiple sensor units are operated close to each other. This prevents interference or crosstalk from occurring between loops connected to different sensor units. A loop transformer within the oscillator circuitry isolates the road loop from the internal circuitry of the sensor improving its resistance to external surges induced in the road loop and also allowing the sensor to operate with loops that are shorted to ground.