... quality analogue voltmeter1 Main Structure and Working Principle1.1 The SCD48, SCD72, SCD96 series square instruments are ... dial and transparentglass cover.1.2 SCD72,SCD96 series DC ammeter, voltmeter, frequency meter, active/reactivepower ... of fire-retardantABS engineering plastics, safe measuring terminals and efficient connection. And it useprinting dial and transparent glass cover. 2.Main Technical ...