Lake Shore Model 331 Temperature Controller User’s Manual
3.4 LINE
INPUT
ASSEMBLY
This section describes how to properly connect the Model 331 to line power. Please follow these
instructions carefully to ensure proper operation of the instrument and the safety of operators.
120
100/120/220/240 V
10% +6% Voltage
50-60 Hz 120 VA MAX
100/120V
220/240V
1.60 A T 250V
0.80 A T 250V
5×20mm
5×20mm
Line Cord
Input
Power Switch
O
= Off,
l
= On
Fuse
Drawer
F-331-3-2.eps
Figure 3-2. Line Input Assembly
3.4.1 Line
Voltage
The Model 331 has four different AC line voltages configurations so that it can be operated from line
power anywhere in the world. The nominal voltage and voltage range of each configuration is shown
below. (The recommended setting for 230 V operation is 240 V.)
Nominal Minimum Maximum
100 V
90 V
106 V
120 V
108 V
127 V
220 V
198 V
233 V
240 V
216 V
254 V
Verify that the AC line voltage indicator in the fuse drawer window shows the appropriate AC line
voltage before turning the instrument on. The instrument may be damaged if turned on with the wrong
voltage selected. Instructions for changing the line voltage configuration are given in Paragraph 8.2.
3.4.2
Line Fuse and Fuse Holder
The line fuse is an important safety feature of the Model 331. If a fuse ever fails, it is important to
replace it with the value and type indicated on the rear panel for the line voltage setting. The letter T
on the fuse rating indicates that the instrument requires a time-delay or slow-blow fuse. Fuse values
should be verified any time line voltage configuration is changed. Instructions for changing and
verifying a line fuse are given in Paragraph 8.3.
3.4.3 Power
Cord
The Model 331 includes a 3-conductor power cord that mates with the IEC 320-C14 line cord
receptacle. Line voltage is present on the two outside conductors and the center conductor is a safety
ground. The safety ground attaches to the instrument chassis and protects the user in case of a
component failure. A CE approved power cord is included with instruments shipped to Europe; a
domestic power cord is included with all other instruments (unless otherwise specified when ordered).
Always plug the power cord into a properly grounded receptacle to ensure safe instrument operation.
The delicate nature of measurement being taken with this instrument may necessitate additional
grounding including ground strapping of the instrument chassis. In these cases the operators safety
should remain the highest priority and low impedance from the instrument chassis to safety ground
should always be maintained.
Installation
3-3
