Reconfiguring the Voltage of Your FG Wilson Generator Set
All Systems:

Under normal conditions, rated power is a constant value for any given generator set model. The formula for Power is: P=(V×A) in a single phase system and P=(V ×√3×A) in a three phase system. If you are reconnecting your generator voltage the current will either decrease or increase in order to equate to the genset's rated constant power value. Using basic algebra, we can figure for current if Power and Voltage are known; e.g., a 100 kVA generator set configured for 415 Volts: A=100×1000/(415×√3). We multiplied 100 (The genset's kVA rating) × 1000, since k is the symbol for kilo, which signifies 1000.

In summary, if you are reconfiguring your generator voltage from a 400 Volt system to a 200 Volt system, your maximum rated current will go up. The opposite is true if you are reconfiguring from 200 Volts to 400 Volts; i.e., your maximum rated current will go down.

When configuring a generator from three phase to single phase, the max amp capacity must be reduced by  1/3. If not, damage the stator windings will occur due to overheating.

The opposite is not necessarily true when converting a genset that was designed for single phase operation.

Analog Control Panels:

200 Volt Three Phase System to a 400 Volt Three Phase System

1) Configure as per section 3.3 (Terminal connection diagrams) of the “Alternators” manual and verify the AVR (automatic voltage regulator) voltage sensing leads have been moved to the correct terminals.

2) The three current transformers should to be changed to a smaller size for maximum scale sensitivity and accuracy. The CT ratings should be equal or slightly greater than the new maximum rated current; e.g., a generator rated for 139 Amps should use CTs rated for 150:5

3) The ammeter must match the primary rating of the current transformers; e.g., a 0 - 150 Amp ammeter for CTs rated 150:5.

4) The voltmeter must be changed from 0-300 to 0-500 VAC

5) The breaker trip setpoint must be lowered to match the new maximum generator current rating.

6) The jumper inside the control panel between wires 115 & 110 must be changed to connect wires 115 & 101. The three wires will be adjacent.

7) Start generator and calibrate voltage to the desired setting. This is accomplished by adjusting the voltage potentiometer on the AVR.

200 Volt Single Phase System to a 400 Volt Three Phase System

1) Configure as per section 3.3 (Terminal connection diagrams) of the “Alternators” manual and verify the AVR (automatic voltage regulator) voltage sensing leads have been moved to the correct terminals.

2) The current transformers should to be changed to a smaller size for maximum scale sensitivity and accuracy. The CT ratings should be equal or slightly greater than the new maximum rated current; e.g., a generator rated for 139 Amps should use CTs rated for 150:5 (When configuring from single to three phase, it may be necessary to add an additional CT)

3) The ammeter must match the primary rating of the current transformers; e.g., a 0 - 150 Amp ammeter for CTs rated 150:5.

4) The ammeter selector switch must be replaced for one that selects three phases

5) The voltmeter must be changed from 0-300 to 0-500 VAC

6) The voltmeter selector switch must be replaced for one that selects three phases. The sensing wires must be reconfigured.

7) The breaker trip setpoint must be lowered to match the new maximum generator current rating.

8) The jumper inside the control panel between wires 115 & 110 must be changed to connect wires 115 & 101. The three wires will be adjacent.

9) Start generator and calibrate voltage to the desired setting. This is accomplished by adjusting the voltage potentiometer on the AVR

400 Volt Three Phase System to a 200 Volt Three Phase System

1) Configure as per section 3.3 (Terminal connection diagrams) of the “Alternators” manual and verify the AVR (automatic voltage regulator) voltage sensing leads have been moved to the correct terminals. (it may be necessary to add an additional cable per phase due to the increase in current)

2) The three current transformers must be changed to ones with higher primary winding ratings. The primary winding ratio must be equal or slightly greater than the new maximum generator current rating; e.g., a generator rated for 262 Amps would use 300:5 CTs.

3) The ammeter must match the primary rating of the current transformers; e.g., a 0 - 300 Amp ammeter for CTs rated 300:5.

4) The voltmeter should be changed from 0-500 to 0-300 VAC for maximum scale sensitivity and accuracy.

5) The breaker must be replaced for one with a higher rating. The rating should match the maximum rated generator current.

6) The jumper inside the control panel between wires 115 & 101 must be changed to connect wires 115 & 110. The three wires will be adjacent.

7) Start generator and calibrate voltage to the desired setting. This is accomplished by adjusting the voltage potentiometer on the AVR.

400 Volt Three Phase System to a 200 Volt Single Phase System (generator must be derated)

1) Configure as per section 3.3 (Terminal connection diagrams) of the “Alternators” manual and verify the AVR (automatic voltage regulator) voltage sensing leads have been moved to the correct terminals.

2) The current transformers must be changed to ones with higher primary winding ratings. The primary winding ratio must be equal or slightly greater than the new maximum generator current rating; e.g., a generator rated for 262 Amps would use 300:5 CTs. (it is not necessary to place a CT on the center tap or neutral)

3) The ammeter must match the primary rating of the current transformers; e.g., a 0 - 300 Amp ammeter for CTs rated 300:5.

4) It may be desirable to replace the ammeter selector switch for single phase selection

5) The voltmeter should be changed from 0-500 to 0-300 VAC for maximum scale sensitivity and accuracy.

6) It may be desirable to replace the voltmeter selector switch for single phase selection. The sensing wires must be reconfigured.

7) The breaker must be replaced for one with a higher rating. The rating should match the maximum rated generator current.

8) The jumper inside the control panel between wires 115 & 101 must be changed to connect wires 115 & 110. The three wires will be adjacent.

9) Start generator and calibrate voltage to the desired setting. This is accomplished by adjusting the voltage potentiometer on the AVR.

Digital Control Panels:

200 Volt Single or Three Phase System to a 400 Volt Three Phase System

1) Configure as per section 3.3 (Terminal connection diagrams) of the “Alternators” manual and verify the AVR (automatic voltage regulator) voltage sensing leads have been moved to the correct terminals. (If configuring from single to three phase, it may be necessary to add an additional CT)

2) The breaker trip setpoint must be lowered to match the new maximum generator current rating.

3) The new system voltage configuration must be programmed in the control panel; e.g., Delta, Wye, etc.

4) The new system voltage must be programmed in the control panel. (the voltage sensing wires may need to be reconfigured if changing between single and three phase systems).

5) Start generator and calibrate voltage to the desired setting. This is accomplished by adjusting the voltage potentiometer on the AVR.

400 Volt Three Phase System to a 200 Volt Single or Three Phase System (generator must be derated if reconfiguring for a single phase system)

1) Configure as per section 3.3 (Terminal connection diagrams) of the “Alternators” manual and verify the AVR (automatic voltage regulator) voltage sensing leads have been moved to the correct terminals. (it may be necessary to add an additional cable per phase due to the increase in current)

2) The three current transformers must be changed to ones with higher primary winding ratings (it is not necessary to place a CT on the center tap or neutral). The primary winding ratio must be equal or slightly greater than the new maximum generator current rating; e.g., a generator rated for 262 Amps would use 300:5 CTs.

3) The new primary CT ratings must be programmed in the control panel

4) The new system voltage configuration must be programmed in the control panel; e.g., Delta, Wye, etc.

5) The new system voltage must be programmed in the control panel. (the voltage sensing wires may need to be reconfigured if changing between three and single phase systems).

6) The breaker must be replaced for one with a higher rating. The rating should match the maximum rated generator current.

7) Start generator and calibrate voltage to the desired setting. This is accomplished by adjusting the voltage potentiometer on the AVR.

Download section_2_ammeters_and_current_transformers.pdf

Download section_3_circuit_breakers.pdf