! Watt and Watt-hour transducers are both phase and polarity sensitive. Incorrect phasing or incorrect positioning of current transformers (CTs) and/or voltage transformers (PTs or VTs) will cause the transducer to register incorrectly.
! The transducer must measure both voltage and current as delivered to the load being measured.
! The number of elements refers to the number of multipliers in the watt transducer. ” 1 element for single-phase, two-wire connections.
” 2 elements for single-phase, three-wire and for three phase, three-wire connections.” 3 elements for three-phase, four-wire connections.
! Most watt and watt-hour transducers require Instrument power. This may be a separate 115-volt AC source or it may be taken from the lines
monitored. Models vary. Check the model number that you have.
! Lightly loaded induction motors consume very little power. If one is testing an unloaded motor, expect power factors below 0.1. If you think this strange, try turning the unloaded motor shaft by hand. Easy isn’t it! The unloaded motor doesn’t require much power to turn. Remember that power in watts is the measure of the rate at which work is being done.
! Watt and watt-hour transducers with analog outputs are easy to check by measuring the analog signal.
! Watt-hour transducers with only a pulse, or closure,output require patience.
! It cannot be emphasize enough — Check and double check wiring for correctness. Phasing and polarity must be correct.! Watt and Watt-hour transducers are both phase andpolarity sensitive. Incorrect phasing or incorrectpositioning of current transformers (CTs) and/orvoltage transformers (PTs or VTs) will cause thetransducer to register incorrectly.! The transducer must measure both voltage andcurrent as delivered to the load being measured.! The number of elements refers to the number ofmultipliers in the watt transducer.” 1 element for single-phase, two-wire connections.” 2 elements for single-phase, three-wire and for threephase,three-wire connections.” 3 elements for three-phase, four-wire connections.! Most watt and watt-hour transducers requireInstrument power. This may be a separate 115-voltAC source or it may be taken from the linesmonitored. Models vary. Check the model numberthat you have.! Lightly loaded induction motors consume very littlepower. If one is testing an unloaded motor, expectpower factors below 0.1. If you think this strange,try turning the unloaded motor shaft by hand. Easyisn’t it! The unloaded motor doesn’t require muchpower to turn. Remember that power in watts is themeasure of the rate at which work is being done.! Watt and watt-hour transducers with analog outputsare easy to check by measuring the analog signal.! Watt-hour transducers with only a pulse, or closure,output require patience.! It cannot be emphasize enough — Check anddouble check wiring for correctness. Phasing and polarity must be correct.