Voltage proving unit

Re-check that the voltage-indicating device is functioning correctly on a known supply or proving unit... 

At the point of work, prove the conductors are dead using a suitable voltage indicator such as test lamps. The voltage indicator must be proven to be serviceable immediately before and after the conductors have been tested for voltage. A proving unit should be used for this, although another live circuit may be used. 

Fig. 7. Fluorescence polarization (FP). (a) The formation of the large FITC—protein A—IgG complex which leads to a net increase in plane polarized light transmitted from the solution. Molecular weights of the protein A-FITC, IgG, and complex are ca 43,000, 150,000, and 343,000, respectively, (b) Detection of IgG by fluorescence polarization immunoassay using A, a laboratory fluorimeter where (O) represents AP = change in polarization, and B, a portable detection unit where (D) is —fiV = change in voltage (27). The field detector proved to be more sensitive than the fluorimeter.

An operation test proves that the preceding tests were valid (i.e. that the unit was switched on for the tests), that the appliances will work when connected to the appropriate voltage supply and will not draw a dangerously high current from that supply. A satisfactory result for this test would typically be less than 3.2 kW for 230 V equipment and less than 1.8kW for 110V equipment. 

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