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Humidity transmitter
testo 6621
Highly accurate testo humidity sensor with long-term
stability (±2.0% RH)
Optional 2-line LCD display
P2A software for parameterization, adjustment and analysis,
saves time and costs in commissioning and maintenance
Wall version with
display
Duct version with
display
Optimum calibration concept thanks to adjustment of the
entire signal chain (1-point, 2-point and analog adjustment)
Adjustment without dismantling the transmitter
2 analog outputs (humidity/temperature), option of 1
passive humidity and temperature analog output
A broad variety of the testo 6621 transmitter is available.
Depending on the application in a room or in a duct,
the corresponding designs can be selected. A display
is available as an option. You can choose between
the housing colours grey and white. The testo 6621 is
persuasive in technical terms thanks to the patented
humidity sensors that guarantee the highest accuracy. The
sensors and the analog outputs can be adjusted, analyzed
and parameterized via the external interface using the P2A
software.
%RH
°C
The testo 6621 is a high-performance transmitter for a low
price. It meets the increasing requirements in automated
building services in terms of accuracy, reliability and safety
and thereby saves energy costs.
www.testo.com
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testo 6621 – Humidity transmitter
Technical data
testo 6621 –
A01/A03 (wall
version)
testo 6621
– A02 (duct
version)
Parameters
Humidity
Meas. range 0 to 100% RH (>90% RH only briefly)
Accuracy* ±2.0 %RH (0 to 90 %RH),
Temperature
dependency/coefficient
Sensor Testo humidity sensor
Replaceability of sensor Through Testo
Temperature
Meas. range 0 to +60 °C
Accuracy ±0,5 °C / 0,9 °F
Sensor Active signal output: NTC
(not for high humidity processes)
±4 %RH (90 to 100 %RH)
Temperature coefficient: 0.05%/K
(gap of 25 °C/77 °F)
Service
(+32 to +140 °F)
Passive signal output: NI1000
Can be done
by customer (s.
below, Replacement
sensors), subsequent
2-point adjustment
required
-20 to +70 °C
(-4 to +158 °F)
Inputs and outputs
Analog outputs
Number of channels 2 channels (humidity and temperature)
Output type
Measuring rate 1/s
Accuracy of analog
outputs
4 to 20 mA (2-wire)
0 to 1/5/10 V (4-wire)
4 to 20 mA ±0,05 mA
0 to 1 V ±2,5 mV
0 to 5 V ±12,5 mV
0 to 10 V ±25 mV
testo 6621 –
A01/A03 (wall
version)
testo 6621
– A02 (duct
version)
General
Housing
Material / colour ABS/
Dimensions 81 x 81 x 26 mm 81 x 81 x 42 mm
Weight 160 g80 g / 90 g (A03)
Display
Display 2-line LCD (optional)
Resolution Humidity: 0.1 %RH
Operation
Parameterization P2A software
Assembly
Cable screw connection None (cable routed
Other features
Protection class IP30 IP65
EMC According to EC directive 2004/108/EEC
Interfaces 1x mini-DIN for connecting PC
Reaction time t90: < 15 s at 2 m/s;
Scaling range -50 to 100 °C / -58 to 212 °F,
pure white (RAL 9010) or light grey
see drawing for
probe
Temperature: 0.1 °C/°F
1 x M16 x 1,5
through rear wall
opening or
break-out opening on
bottom)
For calibration and adjustment, please note:
The response time may be considerably
higher in static air
0 to 100 %RH
Power
Voltage supply 20 to 30 V AC/DC
Current consumption
Output
2-wire current 4 to
20 mA
4-wire voltage 0 to 10V 24 7
* The determination of the measurement uncertainty takes place
according to GUM (Guide to the Expression of Uncertainty in
Measurement):
In the determination, the accuracy of the measuring instrument
(hysteresis, linearity, reproduceability), the uncertainty contribution of
the test site as well as the uncertainty of the adjustment site/works
calibration are taken into account. For this purpose, k=2 of the extension
factor, the usual value in measurement technology, is used as a basis,
corresponding to a trust level of 95%.
Voltage supply [V] Current consumption
[mA]
20 20
24 20
30 30
30 7
20 20
24 22
30 28
Operating conditions
Electronics temperature
(housing) (with/without
display)
Storage temperature -40 to +70 °C (-40 to +176 °F)
Measuring medium Air in air-conditioning systems or air-
0 to +60 °C/32 to +140 °F (A01/A03),
With display: 0 to +50 °C/+32 to +122 °F;
-20 to +70 °C/-4 to +158 °F (A02),
With display: 0 to +50 °C/+32 to +122 °F
conditioned rooms
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testo 6621 – Humidity transmitter
Technical drawings / Connection plan
Technical drawings
testo 6621 – A01
(wall version)
testo 6621 – A03
(wall version)
Connection plan
testo 6621 – A02
(duct version)
A01 Wiring, 3-wire
UrHT
+-+-+123456
+
-
A02 Wiring, 3-wire A02 Wiring, active/passive A02 Wiring, active/passive
1
234
24V~
~
6
5
A01 Wiring, active/passive A01 Wiring A02 Wiring
UrHT
+-+-+123456
654321
+
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-
I
UrHT
+-+-+123456
A03 Wiring
6543
+-+-
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6
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testo 6621 – Humidity transmitter
Options / Ordering example
The following options can be specified for the testo 6621:
AXX Version
BXX Analog output/supply
CXX Display
FXX Humidity parameter
GXX Temperature variable
EXX Housing colour
MXX Protective filter
AXX Version
A01 Wall version (not with B01, B05)
A02 Duct version
A03 Wall version with external probes for 4 to
20 mA analog output (only with B01)
BXX Analog output/supply
2 analog outputs (humidity/temperature)
B01 4 to 20 mA (2-wire , 24 VDC)*
B02 0 to 1 V (4-wire, 24 VAC/DC)
B03 0 to 5 V (4-wire, 24 VAC/DC)
B04 0 to 10 V (4-wire, 24 VAC/DC)
Humidity: analog output temperature: passive,
Ni1000
B05 4 to 20 mA (2-wire , 24 VDC)
B06 0 to 1 V (4-wire, 24 VAC/DC)
B07 0 to 5 V (4-wire, 24 VAC/DC)
B08 0 to 10 V (4-wire, 24 VAC/DC)
CXX Display
C00 without display
C01 with display
FXX Humidity parameter
F01 Relative humidity (%RH)
GXX Temperature variable only for B01 to
B04
G02 Temperature (°C)
G03 Temperature (°F)
EXX Housing colour
E01 Housing colour light grey, incl. Testo logo
(coloured)
E02 Neutral housing, white, without Testo
logo
E03 Neutral housing, white, incl. Testo logo
(black/white)
MXX Protective filter not for A01
M01 Sintered stainless steel filter
M02 Wire mesh protective cap
M03 Sintered PTFE filter
M04 Metal protective cap, open
M05 Plastic cap ABS (open)
Ordering example
Order code for testo 6621 transmitter
with the following options:
- Duct version
- 0 to 5 V (4-wire, 24 V AC/DC)
2 analog outputs (humidity/
temperature)
- Without display
- Relative humidity parameter (%RH)
- Temperature parameter (°C)
- Neutral housing, pure white, without
testo logo
- Metal wire protection cap
0555 6621 A02 B03 C00 F01 G02 E01
M02
0981 8214/msp/I/06.2017Subject to change without notice.
www.testo.com
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