Summary of electrical terminology

• Current (I) = the flow of electricity through an object. Always specify the units used, eg mA RMS for AC; mA average for pDC; mA for DC.

• Voltage (V) = the driving force (electrical pressure). Always specify the units used, eg V RMS. (Remember: even if the required current amplitude is identical for different bird types (eg broiler and egg-laying chickens), the voltage required to achieve this current may differ between the bird types due to their different resistances.)

• Waveform = the shape of one complete cycle of electrical current. Must include the polarity (ie whether AC or DC) and the shape (eg sine, rectangular, the proportion of any clippings of the wave).

• Frequency = the number of complete cycles per second.

• Period = the amount of time taken to complete one cycle of the waveform.

• Pulse width = the amount of time for which the current flows (ie the ‘on’ time) within a single period.

• Duty cycle = the pulse width, expressed as a percentage of the period.

The above parameters should be specified in Standard Operating Procedures (SOPs) for each waterbath stunner on-site (including for each phase of multi-phase stunners) and for each type of bird processed.

Examples of SOPs for electrical waterbath stunning and back-up stunning of poultry can be found in the HSA Guidance Notes No.7 on 'Electrical waterbath stunning of poultry'.

Next: Constant voltage versus constant current electrical stunners