2-38
D
Surge Killers
Install surge killers for loads that have induction coils, such as relays, solenoids, brakes, clutches, etc.
The following table shows types of surge killers and recommended products.
Type
Features
Recommended products
Diode
Diodes are relatively small devices such as relays used
for loads when reset time is not an issue. The reset time
is increased because the surge voltage is the lowest
when power is cut off. Used for 24/48-VDC systems.
Use a fast-recovery diode with a
short reverse recovery time.
Fuji Electric Co., ERB44-06 or equiv-
alent
Thyristor
or
Varistor
Thyristor and varistor are used for loads when induction
coils are large, as in electromagnetic brakes, solenoids,
etc., and when reset time is an issue. The surge voltage
when power is cut off is approximately 1.5 times that of
the varistor.
Select varistor voltage as follows:
24-VDC system varistor:
39 V
100-VDC system varistor: 200 V
100-VAC system varistor:
270 V
200-VAC system varistor:
470 V
Capacitor
+ resistor
Use capacitors and resistors for vibration absorption of
surge when power is cut off. The reset time can be
shortened by proper selection of the capacitor or resis-
tor.
Okaya Electric Ind.
CR-50500
0.5
µ
F-50
Ω
CRE-50500 0.5
µ
F-50
Ω
S2-A-0
0.2
µ
F-500
Ω
Note Thyristors and varistors are made by the following companies. Refer to manufacturers documentation for
operating details.
Thyristors: Ishizuka Electronics Co.
Varistors:
Ishizuka Electronics Co., Matsushita Electric Parts
D
Contactors
When selecting contactors, take into consideration the circuit’s inrush current and the momentary maxi-
mum current. The Servo Driver inrush current is 50 A, and the momentary maximum current is approxi-
mately twice the rated current. The following table shows the recommended contactors.
Maker
Model
Rated current
Momentary maxi-
mum current
Coil voltage
OMRON
J7AN-E3
15 A
120 A
24 VDC
D
Leakage Breakers
•
Select leakage breakers designed for inverters.
•
Since switching operations take place inside the Servo Driver, high-frequency current leaks from the
armature of the Servomotor. With inverter leakage breakers, high-frequency current is not detected,
preventing the breaker from operating due to leakage current.
•
When selecting leakage breakers, also remember to add the leakage current from devices other than
the Servomotor, such as machines using a switching power supply, noise filters, inverters, and so on.
•
For detailed information about the selection methods of leakage breakers, refer to catalogs provided
by manufacturers.
•
The following table shows the Servomotor leakage currents for each Servo Driver.
Driver
Leakage current (direct)
(including high-frequency current)
Leakage current (resistor-capacitor,
in commercial power supply fre-
quency range)
R88D-UEP04V to
-UEP08V
80 mA
3 mA
R88D-UEP12V
60 mA
4 mA
R88D-UEP20V
110 mA
5 mA
System Design and Installation
Chapter 2
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