YASKAWA E7U Programming Manual page 81

Function: Motor Temperature
Setting: E
In addition to or in place of the OL1 (Motor Overload) fault of the Drive, it is possible to use a PTC (Positive Temperature
Coefficient) thermistor for motor insulation protection. The PTC thermistors are built into the windings of some motors and
will vary their resistance based on temperature. An example PTC characteristic is show below.
Connection of the thermistor to the Drive is shown below, in addition make sure Dip Switch S1-2 is in the OFF position, see
Figure 52.
Branch resistance
*1
18 k Ω
PTC Thermistor
*1
using a 3-phase PTC with the characteristics shown in
the figure below.
After the connections are made, configure the A2 analog input for motor temperature protection by setting H3-09= "E: Motor
Temperature". Parameters L1-03, L1-04, and L1-05 set the response to the alarm level being exceeded, response to the fault
level being exceeded, and temperature sensing delay time, respectively.
Resistance (ohms)
1330
550
Tr 5
Fig. 56 PTC Thermistor Temperature-Resistance Value Characteristics
The resistance value of 18 k Ω is only valid for
above.
Fig. 57 Thermistor To Drive Connection Diagram
Class H
Class F
180
150
Tr: Temperature threshold value
Temperature
Tr
Tr Tr+5
+V
(+15 V, 20 mA)
A2
(0-10 Vdc)
Rbranch
AC
Programming 75
( R x3) x ( V -V
ptc@Tr S
=
V
ptc@OH 3
)
ptc@OH 3