Schneider Electric 58 TRX manual Thermal Protection with PTC Probes

Altivar® 58 TRX AC Drives

Drive and Motor Configuration Parameters

6	24	36	60	Hz
5	20	30	50	Hz
t 1 h				ThermProt.eps

10 min

4min

2 min	cold state
1 min
	hot state
10 s	I/In

0.7 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5

Thermal Protection Tripping Curves

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 I2t 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 750Ω (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.

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