3-40
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-V DC 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-V DC system:
39 V
100-V DC system:
200 V
100-V AC system:
270 V
200-V AC system:
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 Industries Co., Ltd.
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 Industrial Co.
D
Contactors
When selecting contactors, take into consideration the circuit’s inrush current and the maximum
momentary current. The Servo Driver inrush current is covered in the preceding explanation of no-fuse-
breaker selection, and the maximum momentary current is approximately twice the rated current. The
following table shows the recommended contactors.
Magnetic Contactors for the W-series
Coil Voltage
Rated current
Order number
Maker
110 V AC
20 A
J7K-BM 110 V 50 Hz OMRON
230 V AC
20 A
J7K-BM 230 V 50 Hz
35 A
J7K-CM 230 V 50 Hz
50 A
J7K-DM 230 V 50 Hz
90 A
J7K-EM 230 V 50 Hz
24 V DC
20 A
J7K-BM-D 24 V DC
35 A
J7K-CM-D 24 V DC
50 A
J7K-DM-D 24 V DC
90 A
J7K-EM-D 24 V DC
Additional Auxillary Contacts for Top Mounting on the Magnetic Contactor
J73K-BM-11
2-pole
1M 1B
OMRON
M = Make contact
J73K-BM-22
4-pole
2M 2B
B = Break contact
J73K-BM-31
p
3M 1B
System Design and Installation
Chapter 3
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