PowerEase
®
300W Power Supply User Guide
11
38B
Edit a program
1.
When a program file is selected the parameters can be edited by the
Mode
key.
2.
The selected parameter will flash. Use the
arrow keys to either increase or decrease
values
3.
Press the
Mode
key to migrate to the next parameter and then to the next step.
39B
View a program
1.
Select the program file number using the
arrow keys, when highlighted press the
Mode
key
2.
Press the
Mode
key to migrate to the next parameter and then to the next step.
15B
Limiting parameter settings
40B
Introduction
The PowerEase
®
300W Power Supply is capable of operating at limiting Voltage, limiting Current,
or limiting Power. We recommend operating the PowerEase
®
300W Power Supply at limiting
voltage for most applications. See below for more details.
41B
Voltage limiting
For most electrophoresis methods resistance increases throughout the run. Limiting the voltage
provides the following advantages:
Current and power decrease throughout the run, providing an improving margin of safety over
time.
The same voltage setting can be used regardless of the number or thickness of gels being
electrophoresed.
42B
Current
limiting
Discontinuous buffer systems and, to a lesser extent, continuous systems increase resistance during
the run. With the current limiting setting on the PowerEase
®
300W Power Supply, the voltage will
increase as resistance increases to satisfy Ohm’s law (V=IR). If no voltage limit is set and a local
fault condition occurs, such as a poor connection, very high local resistance may cause the voltage
to increase to the maximum capacity of the power supply. This may lead to local overheating and
damage to the electrophoresis cell or create unsafe conditions. When operating under constant
current conditions, set a voltage limit on the power supply at or slightly above the maximum
expected voltage.
43B
Power limiting
Power is a function of voltage and current P=IV. For a typical gel run, the current will decrease
causing the voltage to increase when run at constant power. The power limiting function may be
used when running sequencing gels to remove the ammonium persulfate from the wells and to heat
the gel to an optimal temperature for DNA separations.
