Schmidt SS 20.700 User manual

SCHMIDT®Flow Sensor
SS 20.700
Quick Guide

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 2
SCHMIDT®Flow Sensor SS 20.700
Table of Contents
1Important information.......................................................................3
2Application range.............................................................................3
3Assembly.........................................................................................4
4Electrical connection........................................................................6
5Commissioning................................................................................7
6Calculation of volume flow...............................................................7
Imprint:
Copyright 2022 SCHMIDT Technology GmbH
All rights reserved
Version: 562146.02
Subject to modifications

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 3
1 Important information
This quick guide must be read completely and observed carefully, be-
fore putting the SS 20.700 (article number: 562140) into operation.
For detailed information on mounting, operation and conformity
of this sensor, a comprehensive manual (568365.02) is available:
www.schmidt-sensors.com or www.schmidttechnology.de
In case of doubt, please observe the information given there.
Any claims under the manufacturer's liability for damage resulting from
non-observance or non-compliance with these instructions will become
void.
Tampering with the device in any way whatsoever - with the exception
of the designated use and the operations described - will forfeit any
warranty and exclude any liability.
The unit is designed exclusively for the use described below (refer to
chapter 2). In particular, it is not designed for direct or indirect protec-
tion of personal or machinery.
SCHMIDT Technology cannot give any warranty as to its suitability for
a certain purpose and cannot be held liable for accidental or sequential
damage in connection with the delivery, performance or use of this unit.
The corresponding declarations of conformity can also be found at
the above mentioned internet addresses.
2 Application range
The SCHMIDT®Flow Sensor SS 20.700 is designed for stationary meas-
urement of the flow velocity as well as the temperature of air and gases.
The sensor measures the normal velocity wN(unit: m/s), based on normal
conditions of 1013.25 hPa and 20 °C. The output signal is linear and in-
dependent from the pressure and temperature of the medium to be meas-
ured.
When using the sensor outdoors, it must be protected against di-
rect exposure to the weather.
Information and safety instructions for the use in media having an
oxygen percentage of > 21 % can be found in the general Instruc-
tions for Use (568365.02).

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 4
3 Assembly
Determination of installation site
Correct measurements require a flow, low in turbulence. This can be
achieved by providing sufficiently long and straight distances without dis-
turbances in front of and behind the sensor. The minimum run-in and run-
out distances are defined by the type of the flow obstacle upstream of the
measuring distance and the inner pipe diameter D.
Flow obstacle upstream of measuring distance
Minimum distance length of
Run-in (L1)
Run-out (L2)
Light bend (< 90°)
10 x D
5 x D
Reduction / expansion / 90° bend or T-junction
15 x D
5 x D
Two 90° bends in one plane (2-dimensional)
20 x D
5 x D
Two 90° bends (3-dimensional change in direction)
35 x D
5 x D
Shut-off valve
45 x D
5 x D
The sensor may only be mounted and dismounted when no pres-
sure is applied.
In case of mechanical strain (e.g. vibration), the nut of the com-
pression fitting must be secured additionally (e.g. screw lock).
The alignment surface of the sensor’s enclosure must not be used
for countering.
Before pressurization, the pressure-tight assembly as well as the
fastening of the compression fitting and the discarding protection
must be checked. This check must be repeated periodically.
The components of the pressure protection kit (bolt, chain and
bracket) have to be checked regularly for integrity.
Condensing humidity or liquids at the sensor elements will cause
strong deviations of the measured values.
After drying the sensor works correctly again.
Run-in distance L1
Run-out distance L2
Ø D

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 5

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 6
4 Electrical connection
Make sure that no supply voltage is active during electrical instal-
lation and that it cannot be switched on inadvertently.
The flow sensor has two connectors:
Main connector (male, 8-pol):
- Connection of voltage supply
- Output of measuring signals
Module connector (female, 5-pol):
For connection of an optional ex-
tension module.
A supply voltage of 24 VDC ± 20 % / 250 mA is required to operate
the sensor.
For more information, please refer to the general “Instructions for Use”
(568365.02, page 17 et. seq.).
For assignment and wiring of the 8-pole main connector (M12, A-coded,
male), see the following sketch and table.
Depending on the value of the connected load resistances RL, the analog
outputs switch between the operation as voltage interface (0 …10 V) and
current interface (4 …20 mA) automatically.
The switching threshold is set to a load resistance of RL= 500 … 550 Ω.
However, a load value ≤ 300 Ω (I-mode) or ≥ 10 k Ω (U-mode) should be
selected for reliable switchover detection
These loads should be connected to AGND (pin no. 5).
Both pulse outputs provide a frequency which is proportional to flow ve-
locity wN(typ. f = 0 …100 Hz), optionally (by ordering) they output a vol-
ume unit (e.g. 1 pulse/m3).
View on
connector
of sensor

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 7
Pin
Name
Function
Wire colour
1
Pulse 1
Output signal: Flow / volume (pulse)1
White
2
UB
Operating voltage: +24 VDC ± 20 %
Brown
3
Analog TM
Output signal: Temperature of medium (analog: U/I)
Green
4
Analog wN
Output signal: Flow velocity (analog: U/I)
Yellow
5
AGND
Reference potential for analog outputs
Gray
6
Pulse 2
Output signal: Flow / volume (relay)2
Pink
7
GND
Operating voltage: Ground
Blue
8
Pulse 2
Output signal: Flow / volume (relay)2
Red
The specified wire colours are valid when one of the SCHMIDT®connect-
ing cables
3
is used.
The metal sensor enclsure is indirectly coupled to GND (with a varistor,
parallel to 100 nF) and should be connected to a protective potential, e.g.
PE (depending on the shielding concept).
The appropriate protection class III (SELV) respective PELV
(according EN 50178) has to be considered.
Only expansion modules from SCHMIDT Technology may be
connected to the module connector.
5 Commissioning
The valid measuring ranges and the configuration of the signal outputs are
specified on the type plate.
After applying the supply voltage, the sensor signals the initialization of
the measuring operation by means of all four LEDs (sequence: red, or-
ange, green). The flow output signal will at first adopt a higher value and
then settle to the correct measurement value after about 15 seconds.
LEDs flashing in red indicate an error. For detailed error description,
please refer to the general “Instructions for Use”.
6 Calculation of volume flow
SCHMIDT Technology provides a "flow calculator" on its homepage for
the calculation of flow velocity or volume flow in (circular) pipes or (rectan-
gular) ducts for the different sensor types:
www.schmidt-sensors.com or www.schmidttechnology.de
1
Highside driver (connect load to GND = pin no. 7; max. load current = 100 mA)
2
Galvanically decoupled output of relay (max. 30 VDC / 50 mA)
3
All shielded, but cable shield is not connected to cable jack on variant 524942.

Quick Guide –SCHMIDT®Flow Sensor SS 20.700 Page 8
SCHMIDT Technology GmbH
Feldbergstr. 1
78112 St. Georgen
Germany
Phone [phone] / 899-0
Fax [phone] / 899-101
Email [e-mail]
URL www.schmidt-sensors.com
www.schmidttechnology.de