Keithley 7013-S Instruction Manual page 33

Operation
7013
H
1A
IN
FUSE
L
A. Resistor Clamped (AC or DC Voltages)
7013
H
1A
IN
FUSE
L
B. Diode Clamped (DC Voltages)
7013
H
1A
IN
FUSE
L
C. Zener Clamped (AC Voltages)
7013
H
1A
IN
FUSE
L
D. Resistor-Capacitor Clamped (AC Voltages)
Figure 4-1
Limiting inductive reaction voltage
4-2
H
R
Out Load
L
+
H
D
Out Load
L
H
Zener
Diode
Diode
Load
Out
Zener
Diode
L
Diode
H
C
Out Load
R
L
Capacitive loads  The initial surge current from a
capacitive reactive load must be limited. Figure 4-2
shows circuits that can be used to limit current surges.
To protect the relay, limit current to 1A. Also consider
the load when determining the current surge limit.
7013
H
1A
IN
FUSE
L
A. Resistor Limited R = I Limit
7013
H
1A
IN
FUSE
L
High resistance when cold.
*
Low resistance when hot.
Fast thermal recovery.
B. Thermistor Limited Rs = I Limit
Figure 4-2
Limiting capacitive reaction current
R
H
Load
Out
L
V
H
Thermistor*
(Rs)
Load
Out
L
V