NorthStar NP2-120 Single Channel Dual Relay Vehicle Loop Detector, 120 VAC
The NorthStar NP2-120 is a 120 VAC single channel loop detector used in automated gate, access control, and parking systems. It monitors a buried wire loop and changes its relay output when a vehicle enters the loop field. That relay signal can be used by the operator control board for open, reverse, hold-open, safety, or presence functions, depending on how the loop is wired. This model is a good fit for older and current gate control enclosures that are built around 120 VAC detector power and a standard plug-in relay detector layout. The adjustable sensitivity and frequency settings help tune the detector to the loop size, lead-in length, and site conditions, while fault/detect indicators help the installer separate detector problems from loop wiring problems. Match this unit by voltage and connector style, not just by the NP2 name.
Vehicle loop detectors are part of the control side of the gate system. They do not replace photo eyes, gate edges, or other monitored entrapment protection devices required by the operator and current safety standards. A loop detector should be wired only to the input function intended by the operator manufacturer.
Compatible With
Select 120 VAC gate operators, parking gate operators, barrier gate operators, access control panels, and loop detector sockets that accept a standard 11-pin single channel dual relay detector. Commonly used for exit loops, reverse loops, hold-open loops, center loops, shadow loops, and vehicle detection inputs on compatible commercial or residential automated gate systems. Verify that the control panel provides 120 VAC detector power and that the socket or harness pinout matches the NP2 relay wiring.
Features & Specifications
| Manufacturer | NorthStar Controls |
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| Product Type | Single channel dual relay inductive vehicle loop detector |
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| Part Number | NP2-120 |
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| Application | Vehicle detection for automated gates, parking gates, traffic control, and access control systems |
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| Compatible Operator Type | Select gate operators, barrier gates, parking systems, and access controllers with matching detector power and input style |
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| Voltage | 120 VAC / commonly 100 to 135 VAC input |
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| Connection | 11-pin plug-in detector base or compatible harness |
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| Output | Dual relay outputs, commonly listed up to 7A at 277 VAC / 30 VDC |
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| Sensitivity | 10 selectable sensitivity levels |
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| Frequency | 4 selectable loop frequencies |
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| Inductance Range | Commonly 20uH to 1500uH on NorthStar NP2 family detectors; verify the exact data sheet for the installed model |
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| Temperature Range | Commonly -30 F to +180 F on NorthStar detector references |
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| Notes | Match by part number, voltage, socket or terminal style, output type, and control board loop function |
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Also Known As / Related Part Numbers
Technician Note
When replacing a loop detector, do not assume that all NorthStar NP2-style detectors are interchangeable. The detector may share the same general product family while using a different voltage, socket, output type, or low-current connection style. If the loop has nuisance trips, no detection, or fault indications, check the loop and lead-in wiring before blaming the detector.
Before Ordering Checklist
- Match the exact part number from the old detector when available.
- Confirm detector supply voltage in the operator or access control enclosure.
- Check whether the system needs relay output, solid-state output, single output, dual output, or multiple loop channels.
- Verify the socket, plug, terminal strip, or harness style.
- Confirm the loop function: exit, reverse, safety, shadow, hold-open, center, or presence.
- Inspect the loop and lead-in for open, shorted, wet, or damaged wiring before replacing the detector.
Professional Advisory
Loop detector wiring should be handled with the gate operator powered down and according to the operator wiring diagram. For high-voltage detector power, damaged gate wiring, nuisance gate movement, or missing safety devices, use a qualified gate technician. Do not bypass safety inputs to make a detector or gate operator run.
Product Questions & Answers
What is the NP2-120 used for?
The NP2-120 is used with an inductive vehicle loop to send a vehicle detection signal to a compatible gate operator, parking gate, or access control panel.
Will the NP2-120 replace any NorthStar loop detector?
No. Match the original detector part number, voltage, socket or wiring style, output type, and the loop function. Similar NorthStar detector numbers can have different power and connection requirements.
What voltage does the NP2-120 require?
This model is listed for 120 VAC / commonly 100 to 135 VAC input. Confirm the voltage available in the operator control box before installing a replacement detector.
Can the NP2-120 be used for exit or safety loops?
It may be used for exit, reverse, safety, hold-open, or presence loop functions when the operator board supports that input and the detector output is wired correctly.
What should be checked before ordering the NP2-120?
Check the old detector number, loop wiring, socket or terminal style, supply voltage, output contact type, and the gate operator wiring diagram. A qualified technician should handle unsafe wiring or high-voltage service.
