Monitoring functions and protective functions
9.5 Thermal motor protection
Drive functions
Function Manual, 11/2017, 6SL3097-4AB00-0BP5
641
Damage to the motor when operated without temperature sensors
The thermal model cannot protect the motor in the event of incorrect installation, elevated
ambient temperature, or incorrect parameter assignment, and as a consequence, the motor
can be damaged.
• Comply with the motor installation regulations.
• Commission the motor as specified.
Thermal motor model 1 is only used for selected synchronous motors, and protects against
brief overload conditions. It is based on a continuous current measurement. The dynamic
load of the motor is determined from the motor current and the motor model time constant.
The actual value of the motor winding temperature can be measured using a temperature
sensor and subsequently taken into account.
The model motor temperature is indicated in r0632. It is calculated from the following values:
● Absolute current actual value r0068
● I2t motor model thermal time constant p0611
● Motor stall current p0318
● Measured motor temperature r0035 (if available)
● Motor temperature at rated load p0605 (for expansion p0627)
Commissioning the motor model
You activate the thermal I2t motor model with p0612.00 = 1. The expansion makes it more
transparent when setting the motor model. You can additionally activate this expansion using
p0612.08 = 1.
Note
When commissioning the motor, thermal motor model 1 (p0612.00
= 1) including expansion
= 1) is automatically activated.
Preconditions for automatic activation:
•
Rotating permanent-magnet synchronous motors are used
There is no motor sensor
No (other) thermal motor model is activated
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