Indian Standard : box spanners -- specification  section 2 vector sum VAh meters 

 - New Delhi  Bureau of Indian Standards  1990 
 - 6p.  
<br/><br/> IS 2030 : 1989 
<br/><br/><label>Subjects--Topical Terms: </label><br/>AC electricity meter<br/>Indian Standard<br/>Volt-ampere-hour-meter