Choosing Limiting Parameter Settings - VWR 700-0450 Manuel D'instructions

Viewing a Program
1. Select the PROG # using the ▼▲ arrow keys when highlighted press the
Mode key.
2. Press the Mode key 3 more times to advance to the programming.
3. If multiple steps use the Mode key to advance through the program to the
next step.
Editing a program
1. When a file is selected the parameters can be edited by the Mode button
2. When the parameter is selected, it will flash. Use the ▼▲ arrow keys to
either increase or decrease values.
3. Press the Mode key to migrate to the next parameter.
4. When the parameter is selected use the ▼▲ arrow keys to increase or
decrease the values.

Choosing Limiting Parameter Settings

Introduction
The 300 Volt Hi Amperage Power Supply is capable of operating at limiting Voltage,
or limiting Current or limiting Watts. We recommend operating the 300 Volt Power
Supply at limiting voltage for most applications. See below for more details.
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.
Current Limiting
Discontinuous buffer systems and, to a lesser extent, continuous systems increase
resistance during the run. If you use the current limiting setting on the 300 Volt 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.
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