Honeywell NXL - Manual (Page 50)

50(96) Cabling and connections Honeywell Honeywell Honeywell Honeywell
6
6.2.6 Motor thermistor (PTC) connection
There are three possibilities to connect a PTC resistor to NXL:
1. With optional board NXLOPTAI. (Recommended method. Board included in NXL HVAC as standard)
NXL equipped with NXLOPTAI fulfils IEC 664 if the motor thermistor
is insulated (= effective double insulation).
2. With optional board NXOPTB2.
NXL equipped with NXOPTB2 fulfils IEC 664 if the motor thermistor
is insulated (= effective double insulation).
3. With the digital input (DIN3) of NXL.
The DIN3 is galvanically connected to other I/O's of NXL.
This is why reinforced or double insulation of the thermistor (IEC 664) is absolutely required outside
the frequency converter (in the motor or between the motor and the frequency converter).
Figure 6-26. Motor thermistor (PTC) connection
Note! The NXL trips when PTC impedance exceeds 4,7 kΩ
+24 V (terminal 6)
DIN3 (terminal 10, par.2.1.18 = 14)
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External PTC Resistor
GND (terminal 11)
External resistor
4.7 kΩ...5.6 kΩ
It is strongly recommended to use NXLOPTAI or NXOPTB2 board for motor thermistor connection.
If the motor thermistor is connected to DIN3, the instructions above must be followed; otherwise a
serious safety hazard may result from the connection.