Carlo GavazziLDD1PA2DU24Single-Loop Inductive Vehicle Loop Detector, DIN Rail, 24-240 V AC/DC, 2 x SPDT Relay, 20-1000 uH

Product Description

What this part is

A Carlo Gavazzi LD-series inductive loop detector for vehicle detection — the electronics that sense a car, truck or bus sitting over a wire loop buried in the road surface and switch a relay to raise a barrier, open a gate, drop a bollard or trigger a ticket machine. This is the single-loop, DIN-rail, screw-terminal version, 22 mm wide, with two SPDT relay outputs and a 10-step front sensitivity potentiometer.

Decoding the order code

LD – loop detector seriesD (third character) – DIN-rail housing with screw terminals; LDP is instead the plug-in version using an 11-pin circular base such as the ZPD11A socket1 – single loop input (a 2 here, LDD2, is the dual-loop version with directional logic)PA2 – 2 x SPDT relay outputsDU24 – universal supply, 24 to 240 V AC/DC

What these specs mean in practice

Two things decide whether this unit fits an existing installation. First, LDD is DIN-rail with screw terminals — it will not drop into an 11-pin plug-in base, which is what an LDP1PA2DU24 needs. Second, this is the single-loop model: both SPDT relays are assigned to loop 1, so you get two independently configurable outputs from one loop but no direction sensing. Directional logic requires the dual-loop LDD2, which splits the relays one per loop. Beyond that the unit is deliberately flexible: the supply takes anything from 24 to 240 V, AC or DC, and each output can be set to presence mode (relay held while a vehicle sits on the loop) or pulse mode with selectable pulse length and entrance-or-exit triggering.

Published specifications

Type: single loop, DIN-rail mountLoop input inductance: 20 to 1000 µHAdjustable sensitivity: 0.01% to 1.00%, 10 steps via front rotary potentiometerFrequency channels: 4, automatic tuning or manual DIP selectionFrequency range: 10 to 130 kHzResponse time: 130 msLoop fault detection: short circuit, open circuit, inductance out of range, frequency crosstalkOutputs: 2 x SPDT relay, both assigned to loop 1, independently configurable pulse or presence via DIP switchOutput rating: 250 V AC/DC; AC1 5 A at 250 V AC, DC1 1 A at 30 V DCMechanical life: 15 x 10&sup6; operations; electrical life >100,000 operations at 5 ASupply: 24 to 240 V AC/DC, 45 to 65 HzPower consumption: Power-on delay: 5 s manual frequency tuning, 10 s automaticRated insulation voltage: 800 V; impulse withstand 4 kV (1.2/50 µs)Protection: reverse polarity, overvoltage and output transientsAmbient temperature: −40 to +70 °C operating and storage; humidity 0 to 90%Overvoltage category III, pollution degree 2Degree of protection: IP20Housing: PX9406-802 PPO Noryl SE1, RAL 7035 grey, 84 mm (h) x 22 mm (w) x 99 mm (d)Weight: 134 gApprovals: CE, cULus

Quantity and configuration

Sold as 1 piece — the detector module only. The loop wire, feeder cable and any sealing compound are site materials and are not included; no plug-in base is needed or supplied because this version uses screw terminals.

Installation and setup notes

The installed loop must present 20 to 1000 µH at the detector or it will report a fault rather than detect — that is what the multicolour Loop LED is for, distinguishing inductance too high, too low, open circuit and short circuit. Leave automatic frequency tuning on where loops are close together; the four manual channels exist for cases where you want fixed, predictable frequencies, at the cost of a longer commissioning walk. Turn on Automatic Sensitivity Boost (ASB, DIP selectable, indicated by a blue power LED) for high-bed traffic such as buses, trucks and trailers, which otherwise sit too far above the loop for reliable detection. Choose fail-safe or fail-secure deliberately: on power loss or loop fault the output can be configured to indicate detection (barrier opens) or no detection (barrier stays closed). A flashing power LED means a DIP switch has been moved but the change has not been applied — press the reset button.

Interchange guidance

LDD1PA2DU24 and LDP1PA2DU24 are the same detector in different bodies and are not interchangeable: the LDP is a 35.5 mm plug-in unit for an 11-pin circular base, IP30, 105 g. LDD2PA2DU24 is the dual-loop DIN-rail version and adds directional logic, so it is an upgrade rather than an equivalent — and its relay assignment is one per loop, which changes the wiring. Generic loop detectors from other makers are not drop-in replacements: terminal order, relay assignment and DIP function differ.