Schmidt SS 20.515 LED User manual

SCHMIDT®Flow Sensor
SS 20.515 LED
Instructions for Use

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 2
SCHMIDT®Flow Sensor
SS 20.515 LED
Table of Contents
1Important Information ......................................................................3
2Application Range ...........................................................................4
3Mounting Instructions ......................................................................4
4Electrical Connection.......................................................................7
5Signalizing .......................................................................................9
6Startup...........................................................................................11
7Information concerning Operation.................................................12
8Service Information........................................................................13
9Technical Data...............................................................................14
10 Declarations of Conformity............................................................15
Imprint:
Copyright 2022 SCHMIDT Technology GmbH
All rights reserved
Version: 551743.02D
Subject to modifications

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 3
1 Important Information
These instructions for use contain all required information for a fast com-
missioning and a safe operation of SCHMIDT®flow sensors of the
SS 20.515 LED type:
These instructions for use must be read completely and observed care-
fully, before putting the unit into operation.
Any claims under the manufacturer's liability for damage resulting from
non-observance ornon-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 in these instruc-
tions for use - 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 and machinery.
SCHMIDT Technology cannot give any warranty as to its suitability
for certain purpose and cannot be held liable for accidental or sequen-
tial damage in connection with the delivery, performance or use of this
unit.
Symbols used in this manual
The symbols used in this manual are explained below.
Danger warnings and safety instructions - please read them!
Non-observance of these instructions may lead to personal injury
or malfunction of the device.
General information
All dimensions are given in mm.
!

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 4
2 Application Range
The SCHMIDT®Flow Sensor SS 20.515 LED (551550) is designed for
stationary use in cleanrooms under atmospheric pressure and clean envi-
ronmental conditions.
The sensor measures the flow velocity of the gaseous medium (reference:
air) as standard velocity
1
(unit: m/s), relative to standard conditions of
1013.25 hPa and 20 °C.
Thus, the resulting output signal is independent of pressure and tempera-
ture of the medium to be measured.
The sensor is designed for the use inside closed rooms and is not suitable
for outdoor use.
3 Mounting Instructions
General information on handling
The SCHMIDT®Flow Sensor SS 20.515 LED is a sensitive measuring
instrument. Applying mechanical force to the sensor tip should be avoided.
The sensor tip can be damaged irreversibly due to mechanical
stress.
Leave the protective cap as long as possible attached during
mounting and handle the sensor with care.
For applications with an uncontrollable risk of touch, two special safety
bars can be mounted on the sensor (optional accessory). One bracket
consists of a single, very robust spring steel strip (531026) and the other
one comprises two parallel, relatively flexible spring steel wires (559124).
For details, see:
www.schmidt-sensors.com or www.schmidttechnology.de
Flow characteristics
To avoid false measurement results, appropriate installation conditions
must be guaranteed to ensure that the gas flow is supplied to the sensor
in a quiet (low in turbulence) state.
Correct measurements requires laminar2flow with as low turbu-
lence as possible.
1
Corresponds to the real velocity under standard conditions.
2
The term “laminar” means here an airflow low in turbulence (not according to its physical
definition saying that the Reynolds number is < 2300).
!
!

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 5
Mounting sequence
For the assembly of the SCHMIDT®Flow Sensor SS 20.515 LED, five
different assembly versions optimized for use in cleanrooms are available,
in order to cover all the different applications (see Table 1).
First, the required holes, depending on the assembly version, must be
drilled, and the corresponding fixing socket must be mounted in that hole.
Then the connecting cable is introduced with its open into the fixing socket
from the cleanroom side until the cable bushing protrudes from the fixture
by only about 5 cm. Please note that after assembling the sensor, there
must still be room for this protruding cable length in the void behind the
assembly bushing. Now connect the sensor to the connecting cable (plug
in and screw down spigot nut), insert it into the fixture bushing and tighten
the holding fixture screw by hand. Now the sensor can still be aligned ac-
curately by hand, if required. Finally, the holding fixture screw must be
tightened with a key wrench (wrench size 22) until the sensor is sufficiently
secured against twisting.
Prior to commissioning the sensor, remove the protective cap.
Mounting beneath a ceiling
The angled sensor is designed for mounting beneath a ceiling.
After screwing the sensor into the ceiling sleeve, its tip is automatically in
the correct position to measure a vertical downdraft flow from the filter
outlet. Only the torsional angle of the sensor arm in parallel to the ceiling
must still be aligned. Then tighten assembly screw using the key wrench
until the sensor is secured against twisting (hold sensor, if necessary).
Mounting at a wall
The straight sensor is designed for assembly at a wall.
Insert sensor into the fixture bushing and thoroughly tighten the assembly
screw. No alignment to the flow is required, due to the omnidirectional
measurement characteristic of the sensor head.

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 6
Mounting
Drawing
Assembly
Type 1
Threaded bush M25 with lock nut:
- For installation in ceilings, walls or frames
with a thickness from 1… 22 mm
- Opening with Ø of 26 mm required for fix-
ing with lock nut
- Or insert a thread M25 x 1.5 into ceiling
Type 2
Threaded bush M25 with threaded adapter
M25 x 1.5 for PG:
- For installation in frames featuring an ex-
isting opening with PG21 thread
(e.g. sprinkler openings in profiles)
Type 3
Threaded bush M25 with shank nut:
- For installation in frames with a height of
21 … 40 mm, especially for ceiling frames
made of hollow profiles
- Openings with Ø of 26 mm and 28.5 mm
are required
Type 4
Welding bush:
- For welding to ceilings or walls made of
stainless steel
Type 5
Flanged bushing:
- For mounting under the ceiling or at a wall
with two screws M6
- Opening in ceiling / wall required with a
Ø of 15 mm for cable plus 2 threads M6
- Pressure-tight till 300 mbar
Table 1

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 7
4 Electrical Connection
The SCHMIDT®Flow Sensor SS 20.515 LED is equipped with a plug-in
connector firmly integrated into the enclosure with the following data:
Number of connection pins: 7 (plus shield connection of metallic housing)
Type: Male
Locking of connecting cable: M9 spigot nut (on cable)
Model: Binder, series 712
Pin numbering:
View on connector of sensor
Figure 4-1
The pin assignment of the plug-in connector can be found in Table 2.
Pin
Designation
Function
Wire colour
1
Power
Supply voltage: +UB
White
2
Aout Temp
Medium temperature signal TM
Brown
3
Internal
-
Green
4
Internal
-
Yellow
5
Internal
-
Grey
6
Aout Flow
Flow velocity signal wN
Pink
7
GND
Supply voltage: Mass
Blue
Shield
Electromechanical shielding
Shield meshwork
Table 2
All signals use GND as electrical reference potential.
The wire colours mentioned in Table 2 are applicable for the use of a
SCHMIDT®cable (article numbers: 505911-4, 535279, 535281, 565072,
561972, 561973).
The cable shield is electrically connected to the metallic housings of con-
nector and sensor which are coupled to GND indirectly (VDR
3
, in parallel
with 100 nF). The shield should be connected to an anti-interference po-
tential, e.g. ground (depending on the shielding concept).
The appropriate protection class III (SELV) respective PELV
(EN 50178) has to be considered.
During electrical installation ensure that no voltage is applied and
inadvertent activation is not possible.
3
Voltage dependent resistor; breakdown voltage 27 V @ 1 mA
!
!

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 8
Operating voltage
The SCHMIDT®Flow Sensor SS 20.515 LED is protected against a po-
larity reversal of the operating voltage.
It has a nominal operating voltage range of UB= 24 VDC ± 10 %.
Only operate the sensor within the defined operating voltage
range (21.6 … 26.4 VDC).
Undervoltage may result in malfunction, overvoltage may lead to
irreversible damage.
The specifications for the operating voltage are valid for the connection at
the sensor. Voltage drops generated due to line resistances must be con-
sidered by the customer.
Current consumption of the sensor is typically 60 mA and at maximum
100 mA.
Analog signal outputs
The analog outputs of the sensor (flow velocity and temperature of the
medium) are protected against a short circuit towards both rails.
There are two output versions (selected by ordering):
Current interface:
Signal range
4
: 4 ... 20 mA
Type: High side driver, load resistance against GND
Maximum load resistance RL: 300 Ω
Maximum load capacitance CL: 10 nF
Maximum cable length: 100 m (recommended)
Wiring:
Figure 4-2
Voltage interface:
Signal range: 0 ... 10 V
Type: High side driver, load resistance against GND
Minimum load resistance RL: 10 kΩ
Maximum load capacitance CL: 10 nF
Maximum short-circuit current: 25 mA
Maximum cable length: 10 m (recommended)
Wiring:
4
Error signaling 2 mA as specified in NAMUR NE 43
!

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 9
Figure 4-3
Due to the resistance
5
RWof the connecting cable, the operating current
causes a voltage drop in each wire of the operating voltage, which may
adopt interfering values especially as so-called "mass offset" in the GND
wire.
This is why you have to make sure during installation that the original
lead of the sensor is kept as short as possible. Reconnection to cables
with wider cross-sections near the sensor is recommended.
The voltage drop in the GND wire of the connecting cable during
operation can substantially falsify the analog signal at the volt-
age output.
5 Signalizing
The SCHMIDT®Flow Sensor SS 20.515 LED maps the respective meas-
uring quantity linearly to the corresponding analog output. The represen-
tation specification depends both on the measuring quantity and the out-
put characteristics (see figures in the following tables).
Representation of measuring range:
The measuring range of the flow velocity wNextends from zero flow to
the selectable maximum value wN,max (see Table 3).
The measuring range of the temperature of the medium TMis fixed
between -20 °C and +70 °C (see Table 4).
Note regarding commissioning:
Normally the temperature output provides approx. 5 V resp. 12 mA be-
cause the typically prevailing room temperature of approx. 25 °C cor-
responds to half of the measuring range.
Overflow:
Flow speeds which exceed the measuring range are furthermore out-
put in a linear way up to 110 % of measuring range (11 V or 21.6 mA).
For higher values of flow velocity the output signal remains constant.
5
The specific resistance of the lead of the nominal cable (0.14 mm2) is 0.138 /m (20 °C);
at L = 10 m a current of IB,max = 100 mA can cause a voltage drop up to 166 mV.
!

Instructions for Use - SCHMIDT®Flow Sensor SS 20.515 LED Page 10
wN: Voltage interface (U)
wN: Current interface (I)

 

 󰇛 󰇜
Table 3
TM: Voltage interface (U)
TM: Current interface (I)
 󰇡 
  󰇢
  
󰇛 󰇜
Table 4
Temperature of medium outside of specification range:
Operation outside the specified limits may damage the sensor and is
displayed as follows (see also graphics in Table 4):
oTemperature of medium below -20 °C
The analog output for TMswitches to error (0 V or 2 mA).
The analog output for wNswitches to error (0 V or 2 mA).
oTemperature of medium above +70 °C
Measuring values above TM,max are output in a linear way up to ap-
prox. 75 °C (10.6 V or 20.9 mA).
UOut
[V]
075 T
M [°C]
10
4
2
20
11
40 7060-20
6
8
075 20 40 7060-20
IOut
[mA]
T
M [°C]
20
4
8
22
1212
16
2
075 20 40 7060-20 0 75 20 40 7060-20