Hvac Application - Additional Parameter Information - Siemens BT300 Applications Manual

Siemens Application
3.6

HVAC Application - Additional parameter information

Due to its simplicity of use, most parameters of the Siemens Application only require a basic description,
which is given in the parameter tables in Chapter 3.5.
In this chapter, you will find additional information on some of the more advanced application
parameters. Should you not find the information you need, please contact Technical Support.
Motor current limit (P3.1.1.7)
This parameter determines the maximum motor current from the drive. The parameter value range dif-
fers from size to size.
When the current limit is active, the drive output frequency is decreased.
NOTE: This is not an over-current trip limit.
U/f ratio selection (P3.1.2.9)
Selection
Selection name
number
0 Linear
1 Squared
Over-voltage controller (P3.1.2.15)
Under-voltage controller (P3.1.2.16)
These parameters allow the under-/overvoltage controllers to be switched out of operation. This may be
useful, for example, if the mains supply voltage varies more than -15% to +10% and the application will
not tolerate this over-/under-voltage. In this case, the regulator controls the output frequency taking the
supply fluctuations into account.
24-hour support +1-800-877-7545 (Dial 2)
The voltage of the motor changes linearly as a function of output fre-
quency from zero frequency voltage (P3.1.2.4) to the field weaken-
ing point (FWP) voltage at FWP frequency. This default setting
should be used if there is no special need for another setting.
The voltage of the motor changes from zero point voltage (P3.1.2.4)
following a squared curve form from zero to the field weakening
point. The motor runs under-magnetized below the field weakening
point and produces less torque. Squared U/f ratio can be used in
applications where torque demand is proportional to the square of
the speed, e.g. in centrifugal fans and pumps.
U[V]
Default: Nominal
voltage of the motor
Linear
Squared
Figure 14. Linear and squared change of motor voltage.
Siemens Industry, Inc. • 71
Description
Field
weakening
point
Default:
Nominal frequency
of the motor
f[Hz]
11117.emf
3