Depending on the size of bottle cap, a limit may occur in the inverter (power supply), preventing full output power from being obtained. This condition occurs when the load on the inverter is higher than it can deliver, in other words, if there's a large amount of foil running under the coil at one time. If the power meter reading on the front panel of the power supply decreases when there are bottles under the coil, you may need to change the output transformer tap.
An output transformer load compensating selector switch is available to change the output taps on the inverter. The switch is located on the back of the inverter enclosure. The switch is interlocked to the control circuits so the power supply will turn off prior to a tap change. The use of this switch eliminates the need to remove the inverter enclosure cover in order to change taps.
Output transformer tap selector switches come in useful for contract packagers that seal a variety of cap sizes.