Tap switching power supply apparatus and methods for supporting multiple input voltages
A device and method(s) for implementing an AC line-powered primary-tap switching power supply which is easily or automatically switchable between a first configuration which supports a first input voltage, e.g., a 120 VAC input voltage, and a second configuration which supports a second input voltage, e.g., a 240 VAC input voltage, which is an integer multiple of the first input voltage, is described.
1. A multi-mode transformer system supporting at least first and second modes, the system comprising:
a first set of primary transformer windings including a first set of taps, said first set of taps including a first lower tap and a first plurality of upper taps, each of the first plurality of upper taps corresponding to a different input voltage during a first (120V) voltage range mode of operation;
a second set of primary transformer windings including a second set of taps, said second set of taps including a second lower tap and a second plurality of upper taps, each of the second plurality of upper taps corresponding to a different input voltage during said first(120V) voltage range mode of operation, different input voltages supported by said second plurality of upper taps also being supported by the first plurality of upper taps;
a relay assembly configured to control which tap in the first plurality of upper taps is connected to a first input line during said first (120V) voltage range mode of operation and which tap in the second plurality of upper taps is connected to the first input line during the first (120V) voltage range mode of operation, said relay assembly being configured to control which tap in the first plurality of upper taps is connected to the first input line during a second (240V) voltage range mode of operation, the upper taps in the second plurality of upper taps not being connected directly to said first input line during the second (240V) voltage range mode of operation;
a secondary transformer winding with output terminals for coupling to a load; and
one of i) a switch assembly or ii) a jumper device configured to connect at least two taps of said first and second set of taps, said switch assembly or jumper device being configured to connect the first and second lower taps together in parallel to a second input line when operating in said first (120V) voltage range mode of operation and to connect, in series, the first lower tap of the first set of taps to the first upper tap of said second set of taps during said second (240V) voltage range mode of operation, the second lower tap being coupled to the second input line during both said first and second voltage range modes of operation.
2. The multi-mode transformer system of claim 1 , further comprising:
a voltage detection circuit; and
a relay controller configured to activate one of a plurality of relays in said relay assembly when either an input voltage differs from a first input voltage or an output voltage deviates from a target output voltage when operating in the first (120V) voltage range mode of operation and configured to activate one of the relays in the plurality of relays when operating in the second (240V) voltage range mode of operation when either an input voltage differs from a second input voltage (240V) or the output voltage deviates from the target output voltage.
3. The multi-mode transformer system of claim 2 , wherein a number of transformer windings between second and third upper taps of said first plurality of upper taps is the same as a number of transformer windings between second and third upper taps of said second plurality of upper taps.
4. The multi-mode transformer system of claim 3 , wherein a number of transformer windings between third and fourth upper taps of said first plurality of upper taps is the same as a number of transformer windings between third and fourth upper taps of said second plurality of upper taps.
5. The multi-mode transformer system of claim 4 , wherein said first plurality of upper taps includes at least two more taps than said second plurality of upper taps.
6. The multi-mode transformer system of claim 5 , wherein said at least two more taps correspond to voltages for which taps are not included in said second set of upper taps.
7. The multi-mode transformer system of claim 5 , wherein said first (120V) voltage range mode of operation is a 120 volt input mode of operation and wherein said second (240V) voltage range mode of operation is a 240 volt input mode of operation.
8. The multi-mode transformer system of claim 1 , wherein a number of transformer windings between first and second upper taps of said first plurality of upper taps is the same as a number of transformer windings between first and second upper taps of said second plurality of upper taps.
9. The multi-mode transformer system of claim 1 , wherein said multi-mode transformer system includes said jumper device, said jumper device having a first interconnect configuration when the multi-mode transformer system is used in the first (120V) voltage range mode of operation and a second interconnect configuration when the multi-mode transformer system is used in the second (240V) voltage range mode of operation.
10. The multi-mode transformer system of claim 1 , wherein said jumper device is a plug connector that is manually selected and installed at a field location where said multi-mode transformer system is installed based on whether the field location has a 120 volt line or a 240 volt line.