Installation Guide

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Installation and calibration manual

HBDF – Mk2 Defrost Sensor

Introduction

The HBDF sensor measures the ice thickness on an evaporator and delivers an analog signal which can be used in a

PLC for controlling the defrost. The sensor is suited for cold rooms, blast freezers and cold stores where temperatures

are below 0°C. If the sensor is used for heat pumps and similar applications, where the evaporator get wet, special

settings are needed. These functionalities are found in the OD (outdoor) version which has both the special settings and

a thin measuring wire.

Besides providing input for a PLC, the sensor can also provide other outputs for systems without a classic PLC. The

sensor has these three outputs.

• Simple analog: Provide a simple analog signal 4-20 mA linear to the ice thickness for a PLC.

• Smart analog: Provide an analog signal when the specified ice thickness is reached and when defrost can be

ended.

• Relay output: In this mode the defrost can be controlled by relays based on parameters in the sensor.

The sensor is equipped with a temperature sensor which detects when the ice is melted and the defrost cycle is

complete. This is a smart solution to avoid unnecessary defrost.

The sensor has a M12 interface like other HB-product sensors and is configured by the HB tool. The product consists of

a box, a ground cable, the measuring wire, and a temperature sensor.

The sensor is based on the capacitive measurement principle and reacts on ice and water between the wire and the fins

in the evaporator. This means the wire must be mounted between fins where ice builds up and the fins must be

grounded.

Summary of content (13 pages)

PAGE 1
Installation and calibration manual HBDF – Mk2 Defrost Sensor Introduction The HBDF sensor measures the ice thickness on an evaporator and delivers an analog signal which can be used in a PLC for controlling the defrost. The sensor is suited for cold rooms, blast freezers and cold stores where temperatures are below 0°C. If the sensor is used for heat pumps and similar applications, where the evaporator get wet, special settings are needed.
PAGE 2
Table of Contents Intoduction ............................................................................................................. 1 Table of Contents ................................................................................................... 1 Safety Instructions .................................................................................................. 2 Installation ..............................................................................................................
PAGE 3
Installation How to install the electronic box and temperature sensor Installation of controller box and temperature sensor if used. 1) 2) 3) 4) 5) The sensor box is installed on the frame of the evaporator. Ground wire should be connected to the frame. We recommend using stainless screw with a star washer/disc and cover/applying silicone grease/compound around the connection to avoid corrosion. It is important that the evaporator fins are connected electrically to ground – it will not work without.
PAGE 4
The end of the wire must be taken outside the evaporator. The terminal connector is mounted on the end of the wire to avoid electrical connection between the wire and the fins. The wire insulation should not be removed The wire is typically mounted on an overfeed evaporator by putting it behind some of the pipes to keep the wire between the fins on the air inlet side.
PAGE 5
Installation on DX evaporators On DX evaporators ice can built up on both the air inlet side on the outlet side and in the middle. It depends on where the pipes closest to the expansion valve is located. If the superheated pipes are on the air inlet side, it means that there is not enough cooling power to form ice build-up. If possible, observe where ice is formed and place both wires and temperature sensor there.
PAGE 6
Installation on heatpumps Many heat pumps installed outside suffers from massive icing in the temperature interval from the freezing point to approx. 6°C. Above this temperature the airflow will melt the ice and below the freezing point the moisture content is lower. For operation in the interval from 0 to 6°C the ice will be wet especially on rainy days which means special precautions have to be taken. The sensor model must be the version suited for heat pumps with a thin measuring wire.
PAGE 7
Wiring the sensor The HBDF Mk2 use screw terminals and a M12 plug for communication and setup. The sensor needs power connection to be setup and to have the correct function of the relays. Wiring the HBDF Mk2 When the wire, ground cable and temperature sensor is mounted on the evaporator it is connected in the box. The picture show the inside of the box and it should be straight forward. HBDF mk2 instruction manual 17 EN September - 2021 WWW.HBPRODUCTS.
PAGE 8
Simple defrost with electric heater. HBDF mk2 instruction manual 17 EN September - 2021 WWW.HBPRODUCTS.
PAGE 9
Sensor configuration All HB-product sensors can be configured using a laptop and a “M12-USB” cable. The software can be downloaded freely on the HB products web page. The configuration data can be stored in the sensor and will be there until erased even without power connection—just like you store data on a memory stick. When you change a value/setting there will be put a check mark next to it and that indicates you have changed something and need to store the data in the sensor.
PAGE 10
Smart analog In this mode the sensor provides an analog signal 4-18 mA linear to the ice thickness until the ice thickness is reached. Then the sensor has a constant output of 18 mA until the temperature reach the specified value indicating that the defrosting is done. At this point the output is 19 mA for a period defined by a parameter. When the time has passed the evaporator should be dry and free from ice – ready for a new cycle.
PAGE 11
Relay In this mode the sensor provides both an analog signal 4-20 mA linear to the ice thickness and keep the relays inactive until the ice layer is reached. When the specified ice layer is reached relay1 is activated and it can be used for controlling the defrost/heating and switching of the compressor. Relay1 is activated until the temperature sensor measures the elevated temperature indicating that the defrosting is done.
PAGE 12
Calibration of the sensor The sensor can be calibrated using three different methods: When typing in the active wire length and the distance between the fins the basic calibration is calculated, and the sensor is working, but the accuracy can be improved by making a zero calibration.
PAGE 13
LED indication 1) Green LED, flash indicates power supply, And DI external start signal is ON. 2) Red LED indicates Defrost mode or sensor error (Outside measuring range). LED signal Green Red ON/OFF/Frequency On or flash Flash (Run-In mode) OFF Flash Flash quickly OFF Functionality Supply voltage connected Run-in start signal / operation.