Delta Electronics VFD-EL manual Resistor-divider

Chapter 4 Parameters

	VFD-EL
	+10V
resistor-divider
R1	AVI
	47kΩ
PTC
	ACM
	internal circuit

Refer to following calculation for protection level and warning level.

1.Protection level

Pr.07.14= V+10 * (RPTC1//47K) / [R1+( RPTC1//47K)]

2.Warning level

Pr.07.16= V+10 * (RPTC2//47K) / [R1+( RPTC2//47K)]

3.Definition:

V+10: voltage between +10V-ACM, Range 10.4~11.2VDC

RPTC1: motor PTC overheat protection level. Corresponding voltage level set in Pr.07.14,

RPTC2: motor PTC overheat warning level. Corresponding voltage level set in Pr.07.15,

47kΩ: is AVI input impedance, R1: resistor-divider (recommended value: 1~20kΩ) Take the standard PTC thermistor as example: if protection level is 1330Ω, the voltage between +10V-ACM is 10.5V and resistor-divider R1 is 4.4kΩ. Refer to following calculation for 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, Pr.07.14 should be set to 2.4.

Revision August 2008, 2ELE, V1.02 4-75