Lakeshore Learning Materials 622 - Manual (Page 14)

Lake Shore Model 620/622/623/647 Magnet Power Supply User’s Manual
Introduction 1-4
Table 1-4. Model 647 DC Output Specifications
SPECIFICATION CURRENT VOLTAGE
Digital Programming Resolution:
Standard/High
10 mA / 1 mA 10 mV / 1 mV
Digital Programming Accuracy 0.1% I
MAX
1% V
MAX
Digital Programming Repeatability 0.01% I
MAX
0.1% V
MAX
Electronic Resolution:
Standard/High
4 mA / 1 mA 1 mV / 1 mV
Electronic Accuracy 0.1% I
MAX
0.1% V
MAX
Display Resolution: Standard/High 10 mA / 1 mA 10 mV / 1 mV
Stability (Drift) at 25 ±1 °C: Percent of full scale
output change over 8-hours under constant line and load after
a 30 minute warm-up.
±0.005% I
MAX
±0.01% V
MAX
Ripple and Noise: 10 Hz to 10 MHz at 1000 VA 40 µA rms 20 mV rms
Temperature Coefficient: Change in output per °C
after 30 minute warm-up.
0.1% I
MAX
0.1% V
MAX
Source Effect: Line regulation for any line change within
the rated line voltage.
0.005% I
MAX
0.05% V
MAX
Load Effect: Load regulation for a load change equal to
maximum voltage in Constant Current Mode or maximum
current in Constant Voltage Mode.
0.1% I
MAX
0.1% V
MAX
Analog Resistance Programming Accuracy:
0 to 10 K Ω produces negative full scale to positive full scale
current or voltage output. 5 K Ω is 0 current.
10% I
MAX
10% V
MAX
Analog Voltage Programming Accuracy:
Voltage input is ±0.01 V/A, ±0.01 V/V.
1% + 100 mA 2% + 100 mV
Monitoring Output Accuracy: Voltage output is
±0.01 V/A, ±0.01 V/V.
1% + 100 mA 2% + 100 mV
1.3 OPERATING CHARACTERISTICS
Many Lake Shore MPS operating characteristics ideally suit it for charge and discharge cycling of
superconducting magnet loads. These characteristics significantly differentiate a Lake Shore MPS from a
conventional MPS. Consider them when choosing the best MPS for a particular application.
1.3.1 True, Four-Quadrant Bi-directional Power Flow
Lake Shore MPS: Sets either positive or negative
current and voltage values. This true, four-
quadrant operation significantly simplifies test
procedures and system design by eliminating
external switching or operator intervention to
reverse current polarity. The smooth, continuous
transition through zero current allows users to
analyze samples at very small current increments
(as small as 1 mA) about zero. Power flow is bi-
directional. Sink power (energy stored in the
magnet) returns to the AC line instead of
dissipating in an energy absorber. The MPS either
transfers power from the AC line to the magnet, or
from the magnet back to the AC line. The MPS
also tolerates AC line faults; in the event of utility
power failure, it draws power from the charged
load to maintain operation until utility restoration.
Energy flows
from magnet to AC line
Energy flows from AC
line to magnet
Energy flows
from AC line to magnet
Energy flows from magnet
to AC line
+V
-V
Output
Voltage
Output
Voltage
-I
Output
Current
+I
Ouput
Current
Figure 1-1. Four-Quadrant Power