______HSD Technological equipment for Automation _____________________________________
5801H0017 Rev. 02 _________________________________________________________ 37/98
7.7.6 Thermal switch
The electro-spindle motor windings are protected by a normally closed bi-metallic switch encased
in the stator. A second bi-metallic switch protects the cooling fan motor.
The two switches are connected in series (see Figure 11.3).
The switches open if temperature reaches a potentially damaging level and close again when
temperature drops to normal operating levels.
This thermal switch system must be connected in series to the machine's safety stop system as
shown in section 9.6.4 .
The series of bi-metallic switches has the following specifications:
DC power 48 VDC MAX
AC power 230 VAC MAX
Current 1.6 A MAX
7.7.7 Cooling fan
The electro-spindle is cooled by a rear
mounted fan.
The fan must be powered up even when the
spindle is not operating.
The fan is independent of the spindle shaft.
This solution gives improved efficiency
compared to shaft mounted fans.
If the fan motor overheats, the fan's own
thermal switch, wired in series with the main
electro-spindle switch, shuts the unit down.
Operation is re-enabled when the fan's
motor drops to a safe operating temperature
again.
Power
230 ± 10% VAC
Cycles/second 50 Hz 60 Hz
Consumption 45 W 39 W
Thermal switch: Bi-metallic switch
The fan's thermal switch only detects fan motor overheating. It cannot detect that
the fan is prevented from turning, unless this causes overheating. For this
reason, check the condition of the fan regularly.
The fan must remain on at all times when the machine is active even if the
electro-spindle is not operating.
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