Lake Shore 625, User Manual

Page: 37 / 132

Lake Shore Model 625 Superconducting MPS User’s Manual
Operation 4-1
CHAPTER 4
OPERATION
4.0 GENERAL
This chapter provides operating instructions for the features of the Model 625 Superconducting Magnet Power Supply.
Computer interface instructions are in Chapter 5.
4.1 TURNING POWER ON
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 it is turned on with the wrong voltage selected. Instructions
for checking line voltage selection are given in Paragraph 3.3.1.
NOTE: It is recommended that the instrument be powered up and operated with the shorting bar in place before
connecting it to a magnet. This will allow the user to setup the supply and become comfortable with its
operation without risk of damage to the magnet.
When the Model 625 is turned on, the display shows the Lake Shore logo and the alarm beeper sounds briefly. After a
few seconds, a “Checking Hardware” message will appear while the instrument does an internal diagnostic and makes
sure everything is working before the output is turned on. Most of the instrument setup parameter values are retained
when power is off with a few exceptions. The output current will always be set to 0 A anytime the instrument is powered
up. The persistent switch heater, if enabled, will be turned off. When the instrument is powered on for the first time
parameter values are set to their defaults, as listed in Table 4-1.
When initialization is complete the instrument will begin its normal reading cycle and current or field readings should
appear on the display. Any error messages will appear in the bottom of the display. Messages listed in Table 7-1,
Instrument Hardware Errors, are related to the instrument hardware and may require help from Lake Shore service. The
messages listed in Table 7-2, Operational Errors, are related to instrument operation and may be corrected with user
intervention.
The Model 625 should be allowed to warm up for a minimum of 30 minutes to achieve rated accuracy.
4.2 DISPLAY DEFINITION
The Model 625 has an 8 line by 40 character vacuum fluorescent (VF) display capable of showing both text and graphic
images. This paragraph describes features of the display that appear during normal operation including current
measurement, voltage measurement, and current programming. Other display configurations appear during parameter
setting and data entry operations. These displays are illustrated in their individual operation paragraphs.
4.2.1 Output Current Display
When the instrument is configured to display in output current, the display will look similar to the display shown in
Figure 4-1. The output current reading and the output voltage reading are displayed using large 11
× 15 block characters.
Below that are the instrument setup parameters including output current setting, current ramp rate, compliance voltage
limit, and remote voltage sense reading. Display setup is described in Paragraph 4.4.
Output I Output V
+60.0000
A
+0.1346
V
Set: +60.0000 A V Limit: 5.0000 V
Rate: 0.1000 A/s V Sense: +0.0085 V
PSH On: 40 mA
Figure 4-1. Model 625 Output Current Display