GE LTC MAP User Manual

 
3-14 

OEM potentiometers that are not powered require power from the LTC-

MAP’s 24 VDC Sensor Power Supply.  To use the LTC-MAP supply, you 

must: 

• 

Select a Voltage Drop Resistor (R

d

). 

• 

Connect the Power Supply wires to the OEM Potentiometer. 

• 

Connect the wires at the Monitor Circuit board. 

In order to use this power, you must first calculate the value of the required 

voltage drop resistor (R

d

).  The voltage drop resistor limits the current and 

voltage across the potentiometer (see Figure 3-8).   

 

Figure 3-8: Typical OEM Potentiometer Powered by LTC-MAP 

To calculate R

d

: 

1.  Determine the value and number of resistors in the potentiometer. 

NOTE: LTC-MAP can accommodate any value or number of tap 

position resistors. 

2.  Calculate the String Resistance (Rs) where: 

Rs = (Resistor Value) x (Number of Resistors).