Connecting Unit - Denco CAIRplus Operation Manual

Electrical Connection
7.1.1 On-site routing of cables and cable penetrations by others
7.2

Connecting unit

7.2.1 Motor protection
50
•
Avoid cable penetrations and routing of cables near doors, dampers, panel
connections and cover strips.
•
Perform all screw connections and cable openings leak-free.
•
The connecting cables in the fan chamber must be long enough to allow the motor
to be moved easily (e.g. for belt tightening).
Separate grounding for each assembly group with an electrical connection is required.
Consider the relevant instructions specified in the enclosed manuals for the accessory
items.
Motor protection with PTC thermistors
Depending on the motor size and type, the AC motors are fitted from 2 to 6 PTC therm-
istors switched in series. The PTC thermistors are embedded in motor windings to
enhance reading of the winding temperature. PTC thermistors are semiconductor
resistors with variable temperature-dependent values.
When the maximum allowed winding temperature of 135 °C is reached, the resistance
reading increases rapidly. This control method and the full motor-protection electronics
deactivates motors.
Notice!
Unlike thermal contacts, PTC thermistors do not wear off. They provide a high
degree of operational reliability due to shock-resistant, pressure-resistant and
vacuum-proof features.
Risk of damage to the unit!
•
Do not apply voltage to separate lead-out sensor, since this would destroy it.
The maximum allowable voltage reading must not exceed 5 V.
•
Wire the sensor only to the motor full protection tripping unit (e.g. 912.MVS 1.0).
Induction effects!
To prevent induction effects for the PTC thermistor circuit DencoHappel recom-
mends to use electrically screened lines, such as JY (st) Y, 2 x 2 x 0.5. Attach
earth screen on one side to the potential equalisation terminal (PE).
ATTENTION
PR-2009-0096-GB • Subject to modifications • R8-10/2015
CAIRplus