8.3.1 PWM interface
The PWM interface consists of an electronic part connecting the
external control signal to the pump. The interface translates the
external signal into a signal type that the microprocessor can
understand.
In addition, the interface ensures that the user cannot get into
contact with dangerous voltage if touching the signal wires when
power is connected to the pump.
470R
36V
100p
110R
BC847B
BC847B
TLP2704
TLP383
68k
2k7
+
-
1
2
3
4
TM060787
Schematic drawing, interface
Pos.
Description
1
Galvanic isolation
2
PWM output
3
Signal reference (without connection to protective earth)
4
PWM input
8.3.2 PWM input signal profile C (solar)
At low PWM signal percentages (duty cycles), a hysteresis prevents
the pump from starting and stopping if the input signal fluctuates
around the shifting point. Without PWM signal percentages, the
pump will stop for safety reasons. If a signal is missing, for example
due to a cable breakage, the pump will stop to avoid overheating of
the solar thermal system.
Max.
10
20
30
40
50
60
70
80
90
100
TM051575
PWM input profile C (solar)
Axis
Value
X
PWM input signal [%]
Y
Speed
PWM input signal
[%]
Pump status
≤ 5
Standby mode: off
> 5 / ≤ 8
Hysteresis area: on/off
> 8 / ≤ 15
Minimum speed
> 15 / ≤ 90
Variable speed from minimum to maximum
speed
> 90 / ≤ 100
Maximum speed
8.3.3 PWM feedback signal
The PWM feedback signal offers pump information like in bus
systems:
•
current power consumption (accuracy ± 2 % of PWM signal)
•
warning
•
alarm.
Alarms
Alarm output signals are available because some PWM output
signals are dedicated to alarm information. If a supply voltage is
measured below the specified supply voltage range, the output
signal is set to 75 %. If the rotor is locked due to deposits in the
hydraulics, the output signal is set to 90 % because this alarm has a
higher priority.
F
E
100
90
80
70
60
50
40
30
20
10
25
50
100
150
200
250
[W]
[%]
A
B
C
D
TM050006
PWM feedback signal, power consumption
Pos.
Description
X-axis Output power consumption [W]
Y-axis PWM output signal in percentage [%]
A
Standby (stop)
B
Alarm stop: fault, blocked pump
C
Alarm stop: electrical fault
D
Warning
E
Slope: 1 W / % PWM
F
Saturation at 70 W
13
English (GB)
