BECKHOFF AL2000 Linear servomotor - Manual (Page 42)

Electrical installation
8.3 Temperature sensor
The coil unit is equipped with two temperature sensors, a PTC­1k and a KTY21­6. The temperature sensors
are used to monitor the temperature in the coil unit. The temperature cable contains four wires.
8.3.1 PTC specification
The PTC­1k sensor exhibits a sharp rise in temperature when the temperature is close to a certain critical
value, and therefore operates as a digital indicator. A gradual temperature signal can, however, not be
generated from this PTC.
At room temperature, the PTC has an electrical resistance of around 65 ohms. As the temperature rises up
to a critical temperature, the resistance exhibits an almost linear rise up to 1000 ohms. Above this
temperature, the resistance rises exponentially. The switching resistance is therefore 1000 ohms. The servo
drive will immediately disconnect the power supply if this resistance is exceeded. This makes it possible to
guard against overheating the motor. The thermal protection contact cable must therefore be properly
connected to the servo drive.
Temperature Resistance
Up to 20° C below the critical temperature < 250 Ω
Up to 5° C below the critical temperature < 550 Ω
Switching resistance > 1000 Ω
Above the critical temperature > 1330 Ω
8.3.2 KTY Specification
The KTY 21­6 sensor has a stable and moderate temperature coefficient. The KTY is able to acquire
temperature measurements up to high values. The sensor is, for this reason, particularly suitable for
monitoring the temperature of the coil unit.
Linear servomotor AL2xxx 42 Version 4.0