Speed Control; Speed Supervision - Siemens LMV37.4 Series Basic Documentation

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HVAC Products

11.8 Speed control

The LMV37.4... controls the fan motor's speed to the setpoint. To ensure that the actual
speed can still be increased when the maximum is reached, the speed is standardized
when the motor is controlled at 95%. Hence, with a speed setpoint of 100%, a speed in-
crease of 5% is still possible.
The control range of the LMV37.4... is +15% / -10%. If this range is not sufficient, error
80 or 83 can occur.
Error Diagnostic code
code
80 1
2
Note
Internal control with a VSD or PWM fan motor must not be activated. Otherwise,
speed variations can occur, resulting from simultaneous control actions from both the
basic unit and internal control.

11.9 Speed supervision

The fan's actual speed is acquired by the LMV37.4... and assessed from a safety point
of view. If the fan does not operate at the speed setpoint, speed control makes a correc-
tive action, trying to reach the setpoint. If it is not reached within a certain period of time,
safety shutdown is initiated. To ensure a high level of availability and safety, a number
of monitoring bands with different response times are defined.
Speed deviation in % points
0...0.5%
0.6...2%
2.1...10%
>10%
Error Diagnostic
code code
83 Bit 0
Valency 1
Bit 1
Valency 2...3
Bit 2
Valency 4...7
Bit 3
Valency ≥ 8
Bit 4
Valency ≥ 16
Bit 5
Valency ≥ 32
Basic documentation LMV37.4...
11 Fan control
Meaning for the LMV37.4... system
Control range limitation at the bottom
Control range limitation at the top
Shutdown time
Speed reached → no shutdown
<8 s
<3 s
<1 s
Meaning for the LMV37.4... system
Lower control range limitation
Upper control range limitation
Interrupt shutdown due to electromagnetic interference
Curve too steep in terms of ramp speed
Interruption of speed signal
Quick shutdown due to excessive speed deviation
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CC1P7546en
01.12.2009