Elliott Sound Products Transformers - Part 3

Field descriptions for TRAFO7 Excel spreadsheet ...

FieldTypeDescription
UdInputSi diode voltage at high current (change this voltage for using valve (tube) rectifiers, or special diodes)
UbrssInputmax. allowed typical peak-peak ripple voltage
IaInputdesired nom. DC output current per coil (ohmic load)
alphaInputcurrent form factor (RMS > average!) 1.5 ... 2
UaminnInputdesired minimum nominal output voltage, to remember your goal
UaminInputminimum nominal output voltage for computation
rhoconstantCopper thermal specific resistance
LInputline length from house mains entry to transformer,one way (metres)
AInputwire cross section area of this line with length L
Rkcomputedresulting line resistance for both ways
UnetzInputnominal effective mains voltage
fnInputmains frequency
tolupInputupper limit of mains voltage variation
tolowinputlower limit of mains voltage variation
computedtransformation ratio
2computedimpedance transformation ratio
Rkscomputedline resistance transformed to secondary, usually very small
fInputactual used transformer loss factor
fcomputedheuristical determined loss factor, no large difference with actually used, unless reason for this is known!
U0effcomputednominal sine AC effective transformer voltage per coil with no load
Ineffcomputednominal sine AC effective transformer current per coil
Incomputednominal sine AC transformer peak current per coil, compare with Imax for a hint for alpha (value is doubled in case of Center circuit, since only one coil at a time is conducting in this rectifier circuit, while both are conducting with pure resistive load)
Imaxcomputedsecondary peak current per coil, also current through diodes, compare with In to avoid core saturation
Idmcomputedaverage diode current
Pacomputedtotal power per winding delivered to load resistor
Pncomputedtotal transformer power, including rectifier power, load power, all coils and factor alpha
PnscomputedPn divided by number of coils (1, 2)
Ua0+computedidle voltage on capacitor, including mains upper Ua0+ tolerance
Ua0computedidle voltage on capacitor, nominal mains
Ua0-computedidle voltage on capacitor, including mains lower tolerance
Usper+computedidle voltage stress on diodes, including mains upper usper+ tolerance
Ua8+computedinfinite capacitor voltage with load and mains upper Ua8+ tolerance, can be used to estimate e.g. amplifier losses
Ua-computedcapacitor voltage (capacitance value Cl), including mains lower tolerance and line losses and ripple, lowest instantaneous value
Ua8computedinfinite capacitor voltage with load, nominal
Ua8bercomputedtryed infinite capacitor voltage with load
rcomputedratio between Ua8 and Ua8ber in %, error of iteration, minimise to 0.0!
Uneffiteration inputnominal effective transformer secondary voltage, this value must be iterated to minimise r
Rvcomputedload resistor that would draw Ia with infinite capacitor
Ricomputed transformer resistance for each coil
Ri+maincomputedeffective transformer resistance for each coil, including line losses
Clcomputedcapacitor size for give ripple, frequency, load
Pdcomputedpower loss per diode
Pgcomputedtotal power loss, sum for all diodes