272 Transactions of the Boy at Society of South Africa. 
The principle of a sluggish regulator is given in fig. 1. 
A contact voltmeter or relay GV acts as an automatic switch for the 
solenoids and So, according to whether the network voltage Y is below or 
above the normal. For normal voltage, the contact maker is half-way 
between contacts 1 and 2. Suppose core of Sj^ is drawn up, then the con- 
tacts gh and ab are closed and the series motor M is joined across the net- 
work, moving the nut IST upwards by means of the screw 0 and cutting 
Fig. 1. — Principle of slug-gish regulator. 
resistance out of the field circuit, so that the generator voltage can rise. 
When contact 2 is closed by the relay, the current through the armature of 
motor M is reversed and resistance is added to the generator field, thereby 
lowering the generator voltage. 
Critical Speed op Sluggish Regulators. — As has already been 
stated, sluggish regulators are suitable as long as the load variations do 
not follow one another too quickly. It might now appear that for rapid 
load fluctuations the speed of the regulator could l)e increased to suit these 
fluctuations, but, as will be shown further down, if this is done, hunting 
i 
