Electrical Connections - Buhler BMD Guía Rápida

BMD

4.2 Electrical Connections

WARNING
Faulty power supply
An improperly connected device may result in damage
The device must be installed by an electrician.
Observe national and international regulations on the install-
ation of electrical equipment.
To install, switch off the machine and connect the device as
follows:
Sensor cover top view
Fig. 2: Pin assignment, top view of sensor cover
The sensor cable must be shielded.
To ensure protective class IP67, only use suitable plugs and
cables. The tightening torque for the plug is 0.1 Nm.
The current should be measured with a suitable ammeter or
alternatively with a load resistor and voltage metering as de-
scribed in the following chapters. The maximum permissible
load resistance is 100 Ω for 12 V and 400 Ω for 24 V.
CAUTION! When connecting, please note the sensor must
either be earthed via the cable shielding or the housing.
4.2.1 Analog Current Output (4...20 mA) - Measurement
Without Load Resistor
The current should be measured with a suitable ammeter as
shown below.
Sensor cover top view
Fig. 3: Measuring the analog 4...20 mA output without load
resistor
4.2.2 Analog Current Output (4..20 mA) - Measurement
With Load Resistor
To measure the currents of the analog current output with a
voltmeter, a load resistor must be connected to the output as
shown below. Depending on the supply voltage, the load res-
BX150103 ◦ 03/2021
Pin/assignment
Standard cable colour
white
brown
green
yellow
grey
pink
blue
red
Housing/shield
istance should be between 25 Ohm and 200 Ohm. A voltmeter
can now be used to measure the voltage which drops over the
respective resistance.
Sensor cover top view
Fig. 4: Connecting the load resistors to measure the analog
4..20 mA output
To determine the respective parameter from the now avail-
able currents or from the current calculated from the voltage
and the load resistor size, the currents must be converted ac-
cordingly using the formulas in chapter Calibration.
4.2.3 Load Resistor Size
The load resistance cannot be selected arbitrarily. It must be
adjusted to the supply voltage of the sensor. The maximum
load resistance can be calculated using the formula (5-1). Or
you can alternatively use the table here.
R / Ω=U / V ∙ 25 (Ω/V) – 200 Ω
max Supply
R in Ω
max
350
400
450
Tab. 1: Determining the load resistance based on the supply voltage
4.2.4 Setting Analog Current Outputs
The assignment of the analog current output is factory preset.
The default configuration uses the total occupancy of fine and
coarse particles (OccupancyRate_sum). However, the sensor
allows changing the preset output parameter. The RS232 com-
mand is: „SAOx[CR]", with the corresponding numerical code
x. The table shows the possible parameters for configuring the
analog outputs.
(5-1)
U in V
supply
22
24
26
Bühler Technologies GmbH 7