Schneider Electric ALTIVAR 58 TRX - Manual (Page 48)

Altivar ® 58 TRX AC Drives
Drive and Motor Configuration Parameters
© 2000–2003 Schneider Electric All Rights Reserved
48
09/2003
Thermal Protection of Motor
This function provides indirect thermal protection of the motor by continuous
calculation of its theoretical temperature rise. The drive controller will fault if
the calculated temperature rise exceeds 118% of the nominal temperature
rise.
For applications using self-cooled or force-cooled motors, the
microprocessor calculates the theoretical temperature rise of the motor using
the following elements:
• Operating frequency.
• Current drawn by the motor.
• Operating time.
• Maximum ambient temperature of 40 °C (104 °F) around the motor.
The following adjustments may be made:
• 0.25 to 1.36 times the nominal current of the drive controller’s constant-
torque rating, preset at 0.9.
• Adjust to the nominal current indicated on the motor rating plate.
NOTE: When the drive controller de-energizes, the I
2
t calculation is saved
and the cooling effect is calculated.
This function may also be used for specialized applications. Thermal
protection may be customized in the fault configuration menu for:
• Applications with force-cooled motors. See the tripping curves at left for
the nominal frequency 50/60 Hz.
• Inhibiting thermal protection in harsh environments where temperatures
exceed 40 °C (104 °F) around the motor or where there is a risk of the
cooling fins becoming clogged. In these applications, provide direct
thermal protection using PTC thermistor probes built into the motor.
• Protection of motor using PTC probes. See “Thermal Protection with PTC
Probes” below.
• In the case of motors connected in parallel on the same controller, each
motor starter must be fitted with a thermal overload relay.
Thermal Protection with PTC Probes
This function provides thermal protection of the motor. The function must be
assigned to analog input AI3 on the I/O Extension Card with Analog Inputs
and the motor must be equipped with PTC probes.
The maximum resistance of the probe circuit at 20 °C (68 °F) is 750
Ω
(3 x
250
Ω
probes in series). The probe break and probe short-circuit faults are
monitored.
Thermal Protection of ATV58 TRX Controller
This function provides direct thermal protection via a thermistor affixed to the
heatsink, thus ensuring component protection even in the case of faulty
ventilation or excessive ambient temperature. When an overtemperature
condition is sensed, the controller will fault on drive overtemperature.
0.7
t
6
5 24
20 36
30 60
50
0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5
hot state
cold state
Hz
Hz
10 min
4 min
2 min
1 min
10 s I/In
1 h
ThermProt.eps
Thermal Protection Tripping Curves