Delta VFD-EL-W Series, User Manual

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Chapter 4 Parameters

VFD-EL-W
4-67
07.12 Motor PTC Overheat Protection Unit: 1
Default: 0
Settings 0 Disable
1 Enable
07.14 Motor PTC Overheat Protection Level Unit: 0.1
Settings 0.1–10.0 V Default: 2.4

Running the motor at low frequency for a long time reduces the cooling function of the motor fan. To prevent
overheating, use a Positive Temperature Coefficient thermistor on the motor, and connect the thermistor
output signal to the drive’s corresponding control terminals.

When you set the source of the first and second frequency command to AVI (Pr.02.00=1 / Pr.02.09=1), you
disable the motor PTC overheat protection (that is, Pr.07.12 cannot be set to 1).

If the temperature exceeds the setting level, the motor coasts to stop and PtC1 ( ) displays. When the
temperature decreases below the level of (Pr.07.15 minus Pr.07.16) and stops blinking, you can press
the RESET key to clear the fault.

Pr.07.14 (overheat protection level) must be greater than Pr.07.15 (overheat warning level).

The PTC function uses the AVI-input and is connected with a resistor-divider as shown in the diagram below.
1. The voltage b10 V to ACM: between 10.4–11.2 V.
2. The impedance for AVI is around 47 kΩ.
3. The recommended value for the resistor-divider R1 is 1–10 kΩ.
4. Please contact your motor dealer for the temperature curve and resistance value for the PTC function.

Refer to the following calculation for the protection and warning levels.
1. Protection level
Pr.07.14 = V
+10
* (R
PTC1
//47k) / [R1+( R
PTC1
//47k)]
2. Warning level
Pr.07.15 = V
+10
* (R
PTC2
//47k) / [R1+( R
PTC2
//47k)]
3. Definition:
V+10: voltage b10 V to ACM, Range 10.4–11.2 V
R
PTC1
: motor PTC overheat protection level; set the corresponding voltage level in Pr.07.14
R
PTC2
: motor PTC overheat warning level; set the corresponding voltage level in Pr.07.15
47 kΩ: the AVI input impedance
R1: resistor-divider (recommended value: 1–10 kΩ)

Example: using a standard PTC thermistor, if the protection level is 1330 Ω, the voltage b10 V to
ACM is 10.5 V and resistor-divider R1 is 4.4 kΩ. Refer to the following calculation for the Pr.07.14 setting.
1330//47000 = (1330*47000) / (1330+47000) = 1293.4
10.5*1293.4 / (4400+1293.4) = 2.38(V)
≒
2.4(V)
Therefore, set Pr.07.14 to 2.4.