Danfoss VLT Series Design Manual page 11

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VLT HVAC Drive Design Guide
Trip
A state entered in fault situations, e.g. if the frequency converter is subject to an over-temperature
or when the frequency converter is protecting the motor, process or mechanism. Restart is pre-
vented until the cause of the fault has disappeared and the trip state is cancelled by activating
reset or, in some cases, by being programmed to reset automatically. Trip may not be used for
personal safety.
Trip Locked
A state entered in fault situations when the frequency converter is protecting itself and requiring
physical intervention, e.g. if the frequency converter is subject to a short circuit on the output. A
locked trip can only be cancelled by cutting off mains, removing the cause of the fault, and re-
connecting the frequency converter. Restart is prevented until the trip state is cancelled by
activating reset or, in some cases, by being programmed to reset automatically. Trip locked may
not be used for personal safety.
VT Characteristics
Variable torque characteristics used for pumps and fans.
VVCplus
If compared with standard voltage/frequency ratio control, Voltage Vector Control (VVC
proves the dynamics and the stability, both when the speed reference is changed and in relation
to the load torque.
60° AVM
Switching pattern called 60°A synchronous V ector M odulation (par. 14-00).
1.1.5. Power Factor
The power factor is the relation between I
and I
RMS
The power factor for 3-phase control:
The power factor indicates to which extent the
frequency converter imposes a load on the
mains supply.
The lower the power factor, the higher the
I for the same kW performance.
RMS
In addition, a high power factor indicates that the different harmonic currents are low.
The frequency converters' built-in DC coils produce a high power factor, which minimises the
imposed load on the mains supply.
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MG.11.B2.02 - VLT is a registered Danfoss trademark
1. How to Read this Design Guide
1
Power factor
=
I cos
× ϕ1
1
= =
I
RMS
2 2
I I I
= +
RMS
1 5
plus ) im-
U I
3 × ×
COS
1 × ϕ
U I
3 × ×
RMS
I
1
since cos
ϕ1 = 1
I
RMS
2 2
I I
+ + . . +
n
7
11
1