Siemens G85139 - Manual (Page 28)

English 5. SYSTEM PARAMETERS
Parameter Function Range
[Default]
Description / Notes
G85139-H1750-U049-B © Siemens plc 1997
26/09/97 28
P066
Compound braking 0 - 1
[1]
0 = Off
1 = On. Permits faster ramp-down times and enhances stopping
capability.
P073
•
DC injection braking (%) 0 - 250
[0]
This stops the motor by applying a DC current. This causes heat to be
generated in the motor rather than the inverter and holds the shaft
stationary until the end of the braking period. Braking is effective for the
period of time set by P003.
The DC brake can be activated using DIN1 - DIN3 (braking is active for
as long as the DIN is high - see P051 - P053).
WARNING: Frequent use of long periods of dc injection braking
can cause the motor to overheat.
If DC injection braking is enabled via a digital input
then DC current is applied for as long as the digital
input is high. This causes heat in the motor.
P074
•
I 2 t motor derating 0 - 1
[1]
0 = Disabled
1 = Enabled. Causes an F074 trip if the motor exceeds the I
2 t calculation.
The time taken to trip is dependent on the difference between the
overload current and the nominal motor current rating stored in P083 -
typically a 150% overload will result in a switch-off in 1 - 2 minutes.
WARNING: Where motor thermal protection is required, an external
PTC must be used.
P076
•
Pulse frequency 0 - 7
[0 or 4]
Sets the pulse frequency (from 2 to 16 kHz) and the PWM mode. If
silent operation is not absolutely necessary, the losses in the inverter
as well as the RFI emissions can be reduced by selecting lower pulse
frequencies.
0/1 = 16 kHz (230 V default)
2/3 = 8 kHz
4/5 = 4 kHz (400 V default)
6/7 = 2 kHz
Note: When P076 = 0/1, the display of the current at frequencies
below 10 Hz is less accurate.
400V inverters require the continuous current rating reduced for
operation below 5Hz, when operating at switching frequencies greater
than 4kHz and with boost values greater than 100% (P078 + P079).
These are typically as follows:
Model P076 =
0 or 1 2 or 3
MM37/3- MM750/3 50%xP083 80%xP083