
Lake Shore Model 340 Temperature Controller User’s Manual
Installation
3-5
3.3 LINE
INPUT
ASSEMBLY
The line input assembly contains the line
voltage selector, line fuse holder, and power
cord connector. It is important to verify that the
Model 340 is set to the appropriate line voltage
and has the correct line fuse before it is
powered on for the first time. Refer to Table 3-2.
If the final destination of the instrument is
known when it is shipped, the line input is
configured at the factory. This configuration
should always be checked because it is not
unusual for an instrument to change hands before it reaches the end user. All of the line voltages discussed
are single phase.
Line voltage and fuse verification is discussed in Paragraph 3.3.1. Line voltage selection is discussed in
Paragraph 3.3.2. Fuse replacement is discussed in Paragraph 3.3.3. The power cord is discussed in
Paragraph 3.3.4. Finally, the power switch is discussed in Paragraph 3.3.5.
3.3.1 Line Voltage and Fuse Verification
To verify the proper line voltage selection look at the indicator in the window of the line input assembly. Line
voltage should be in the range shown in Table 3-1 for that indicator. If it is not, change the line voltage
selector as described in Paragraph 3.3.2. The fuse must be removed to verify its value. Refer to Paragraph
3.3.3 for fuse replacement instructions. Fuses are slow blow (time delay) type and should always be the value
specified in Table 3-1. Fuse values are also printed on the rear panel of the instrument for convenience.
WARNING: To avoid potentially lethal shocks, turn off controller and disconnect it from AC
power line before performing these procedures. Only qualified personnel should
perform these procedures.
CAUTION: For continued protection against fire hazard, replace only with the same type and
rating of fuse as specified for the line for the line voltage selected.
3.3.2 Line Voltage Selection
Below is the procedure to change the instrument line voltage selector. Verify the fuse value whenever line
voltage is changed.
1. Identify the line input assembly on the instrument rear panel.
2. Turn the line power switch OFF (
O
).
3. Remove the instrument power cord.
4. With a small screwdriver, release the drawer holding the line voltage selector and fuse.
5. Slide out the removable plastic fuse holder from the drawer.
6. Rotate the fuse holder until the proper voltage indicator shows through the window.
7. Verify the proper fuse value.
8. Re-assemble the line input assembly in the reverse order.
9. Verify the voltage indicator in the window of the line input assembly.
10. Connect the instrument power cord.
11. Turn the line power switch ON (
l
).
Table 3-2. AC Line Input Definitions
Indicator Line Voltage Range
Fuse (slow blow)
100
90-105 VAC
2 A
120
108-126 VAC
2 A
220
198-231 VAC
1 A
240
216-252 VAC
1 A