CA Datasheet, PDF (7/8 Pages) Littelfuse – Varistor Products - High Energy Industrial Disc

Varistor Products
High Energy Industrial Disc
CA Varistor Series
MODEL
NUMBER
V131CA32
V131CA40
V151CA32
V151CA40
V251CA32
V251CA40
V251CA60
V271CA32
V271CA40
V271CA60
V321CA32
V321CA40
V321CA60
V421CA32
V421CA40
V421CA60
V481CA32
V481CA40
V481CA60
V511CA32
V511CA40
V511CA60
V571CA32
V571CA40
V571CA60
V661CA32
V661CA40
V661CA60
V751CA32
V751CA40
V751CA60
V881CA60
V112CA60
V142CA60
V172CA60
V202CA60
V242CA60
V282CA60
SIZE
(mm)
32
40
32
40
32
40
60
32
40
60
32
40
60
32
40
60
32
40
60
32
40
60
32
40
60
32
40
60
32
40
60
60
60
60
60
60
60
60
TYPICAL DISC
WEIGHT (GRAMS)
9
21
11
23
8
17
39
10
18
42
11
22
50
15
28
66
16
31
71
18
35
80
20
38
88
23
44
101
26
51
116
141
178
220
265
317
377
450
Passivation Layer
The standard CA Series is supplied with passivation layer around the
outside perimeter of the disc forming an electrical insulator as detailed in
the dimensional drawing. The CA Series is also available without a
passivation layer for applications where the customer provides a suitable
encapsulation or potting material as recommended below.
(See Ordering Information.)
Encapsulated Recommendations
After lead attachment, the disc/lead assembly may be coated or
encapsulated in a package to provide electrical insulation and isolation
from environmental contamination as required by the application.
Coating/Filler materials for containers may include silicones,
polyurethanes, and some epoxy resins.Two examples of acceptable
polyurethanes are Dexter Hysol (US7013, parts A and B) and Rhenatech
(resin 4714, hardener 4900), or their equivalents. Materials containing
halogens, sulfides, or alkalines are not recommended.
Electrode Metallization
The standard CA Series is supplied with sintered silver electrodes on
CA32 devices and arc-sprayed copper-over-aluminum electrodes for CA40
and CA60 series. CA40 parts are also available with sintered silver elec-
trode, see “Ordering information.” In general, when discs are stacked to
attain a specific operating voltage or energy capability, the copper finish is
typically chosen. Likewise, the copper finish is used with high temperature
lead attach soldering operations (wave solder). The silver metallization is
typically used for solder reflow lead attach operations (I-R, Vapour-Phase).
The recommended temperature profile of a belt-fed convection oven is
shown in Figure 13.
250
200
150
100
50
0
0 100 200 300 400 500 600 700 800 900
TIME (SEC)
FIGURE 13. TYPICAL BELT OVEN TEMPERATURE PROFILE
Stacking and Contact Pressure
Recommendations
When applications require the stacking of Littelfuse CA discs or when
electrical connection is made by pressure contacts, the minimum pres-
sure applied to the disc electrode surface should be 2.2kGs (5 pounds).
The maximum recommended pressure applied to the disc electrode is
dependent upon diameter size and is given in the following table.
MODEL SIZE (mm)
32
40
60
MAXIMUM PRESSURE
16N/CM² (23LBs/IN²)
8N/CM² (11.5LBs/IN²)
4N/CM² (5.7LBs/IN²)
120
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