GE LTC MAP User Manual

The OEM potentiometer is a voltage divider containing a resistor string. 

Each position on the string represents a tap position.  In the examples in 

this Section, the potentiometers have thirty three positions containing thirty 

two 40-ohm resistors.  The actual number of positions and number and 

values of resistors may be different on your potentiometer. 

The power supplied to the OEM potentiometer depends on the utility.  The 

variations include: 

• 

-5 to +5 VDC or -10 to +10 VDC. 

• 

0 to +5 VDC or 0 to +10 VDC. 

• 

No voltage (connect with LTC-MAP power). 

Determine the voltage across your potentiometer and follow the 

appropriate wiring instructions. 

In general, two signals are utilized between the OEM potentiometer and the 

LTC-MAP.  The signal is a linearly varying DC voltage (+10 V maximum). 

For proper tap position recording by the LTC-MAP, the linearly varying DC 

voltage from the OEM potentiometer must have a uniform increment for 

each tap position.  For example, a potentiometer used for a 33 tap device 

(16 lower, 16 raise, and neutral) with a 10 Volt drop across the entire bridge 

must show a 10V/32 = 0.3125 V change per tap step on the potentiometer 

wiper.