Omron OMNUC U Series User Manual page 56

System Design and Installation
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
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.
Thyristor Thyristor and varistor are used for loads when induction
or coils are large, as in electromagnetic brakes, solenoids,
Varistor 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.
Capacitor Use capacitors and resistors for vibration absorption of
+ resistor surge when power is cut off. The reset time can be
shortened by proper selection of the capacitor or resis-
tor.
Note Thyristors and varistors are made by the following companies. Refer to manufacturers documentation for
operating details.
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
OMRON J7AN-E3
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
R88D-UEP04V to
-UEP08V
R88D-UEP12V
R88D-UEP20V
2-38
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Features
Thyristors: Ishizuka Electronics Co.
Varistors: Ishizuka Electronics Co., Matsushita Electric Parts
Rated current
15 A
Leakage current (direct)
(including high-frequency current)
80 mA
60 mA
110 mA
Recommended products
Use a fast-recovery diode with a
short reverse recovery time.
Fuji Electric Co., ERB44-06 or equiv-
alent
Select varistor voltage as follows:
24-VDC system varistor:
100-VDC system varistor:
100-VAC system varistor:
200-VAC system varistor:
Okaya Electric Ind.
0.5 µF-50 Ω
CR-50500
CRE-50500 0.5 µF-50 Ω
0.2 µF-500 Ω
S2-A-0
Momentary maxi-
mum current
120 A 24 VDC
Leakage current (resistor-capacitor,
in commercial power supply fre-
quency range)
3 mA
4 mA
5 mA
Chapter 2
39 V
200 V
270 V
470 V
Coil voltage