USER'S GUIDE R18 AXIAL FAN , Iss: 6.05.2021
05
SPEED CONTROL DIAGRAM
Rotation speed of a variable speed fan can be controlled by various signals:
- Linear voltage input (0-10V) or current input (4-20mA) or PWM input (PWM duty cycle 0-100%).
- MODBUS RTU protocol (Additional information are in documentation "Hidria EC Modbus parameters".
Linear voltage input is the most common and it is described below. The current input is also widely used, where long cables are necessary. PWM input
is used for electromagnetic noisy environments. PWM signal must be in square form with polarity the same as for linear voltage input (see connection
diagram). PWM duty cycle 0-100% correspond to 0-10V linear voltage input if the amplitude of the PWM voltage is Vp=10V. Amplitude of PWM signal
must not exceed 12Vp.
LINEAR VOLTAGE INPUT:
Linear input is factory adjusted to fit the customer’s sensor or other speed control reference. The input characteristic can be factory adjusted in terms of
increasing input sensitivity or attenuation.
For example: An air-cooled condenser is using a pressure sensor 0-20Bar => 0-10V, but the highest system pressure reached at maximum load is
16Bar => 8V. For optimal operation of the application the fan mounted on a condenser should run at max speed at 8V of input control voltage. In order
to achieve that, we need to adjust the input characteristic in a way the picture shows.
1.0V
1,2V
Input voltage (0
…
10V)
Fa
n
s
p
e
e
d
HYSTERESIS
100%
1.2V
10V
Input voltage (0
…
10V)
Fan speed
CONTROL DIAGRAM
8V
adjusted
input curve
100%
1.2V
10V
Input voltage (0
…
10V)
Fan speed
INPUT CHARACTERISTIC ADJUSTMENT
0
200
400
600
800
1000
1200
Fa
n
r
o
ta
ti
o
n
a
l
sp
e
e
d
(R
P
M
)
Input Voltage (0...10 V)
SPEED CONTROL DIAGRAM
1.2 V
10 V
5 V
O
N
/O
F
F
H
Y
S
T
E
R
E
S
IS
D
=
0
.2
V
In order to prevent cycling from standby to run mode or run to standby
mode a small hysteresis is implemented. The default value is
approximately 200mV.
Hysteresis can be factory-adjusted in order to achieve customer
requirements.
Linear voltage input (0-10V DC) can be used as 0 (4)-20mA current
input with an additional resistor of 500 Ohms between GND and 0-10V
connection.
Speed of a fan increases linearly with input voltage.
The fan operates in two different modes:
0-1.2 V…… Standby or stop mode
1.2-10 V….. Run mode
1.0-1.2V .....Hysteresis
© Copyright HIDRIA d.o.o., All rights reserved. Document is subject to change without prior notification.
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