Arrangement for electrical measurement

An arrangement for determining output electrical quantities from at least two input electrical quantities, wherein the output electrical quantities to be determined include at least one main quantity which is an active energy and one subordinate quantity, and wherein said arrangement comprises

• first input means for receiving a first of said input electrical quantities in the form of a voltage,
• second input means for receiving a second of said input electrical quantities in form of a current associated with the voltage,
• computing means,
• means including a first analog-to-digital converter for transmitting a signal representative of one of said first or second input electrical quantities at said first or second input means, respectively, to said computing means to determine said subordinate quantity,
• a first multiplier for multiplying said first and second input electrical quantities to form an output signal representative of the product of said first and second input electrical quantities, and
• means including a signal-to-frequency converter for receiving said output signal of said multiplier and for transmitting a signal representative of said output signal of said multiplier to said computing means to determine said main quantity,
• wherein the precision and security of said main quantity is greater than the precision and security of said subordinate quantity,
• wherein the output signal of said first multiplier is transmitted by means of a first selector switch to either said signal-to-frequency converter to determine said main output electrical quantity or to an analog-to-digital converter to determine a subordinate output electrical quantity, whereby when said output signal is transmitted to said signal-to-frequency converter said first multiplier receives a signal representative of said voltage via a second selector switch and when said output signal is transmitted to an analog-to-digital converter said first multiplier receives a fixed reference current via a third selector switch.

A multifunction electrical meter arrangement for determining a main output quantity which is active energy with a high security against fraud and a subordinate quantity with a lower security against fraud, said arrangement comprising

• a first input for receiving a current,
• a second input for receiving a voltage,
• a low security circuit including an analog-to-digital converter for outputting a low security signal representative of said current or voltage,
• a multiplier for multiplying said current and voltage and for outputting a signal representative of the product of said current and voltage,
• a high security circuit including a signal-to-frequency converter for outputting a high security signal representative of the output signal of said multiplier, and
• a common digital computer for utilizing the high security signal and the low security signal to output said main quantity with a high security against fraud and said subordinate quantity with a lower security against fraud.