ALC10C331ED450 BHC COMPONENTS, ALC10C331ED450 Datasheet - Page 13

• Manufacturer Part Number: ALC10C331ED450
• Description: CAPACITOR, 330UF 450V CAPACITOR, 330UF 450V
• Manufacturer: BHC COMPONENTS
• Series: ALC10r

Specifications of ALC10C331ED450

• Capacitance: 330UF
• Voltage Rating, Dc: 450V
• Capacitor Dielectric Type: ALUMINIUM ELECTROLYTIC
• Temp, Op. Max: 85(DEGREE C)
• Temp, Op. Min: -40(DEGREE C)
• Tolerance,: 20%
• Rohs Compliant: YES

Advantages
 Simple construction
 Inexpensive
Disadvantages
 Only offers basic protection
 Cannot protect against internal discharges within bank
OPTION 2 - Individual capacitor fuses
Advantages
 Removes faulty capacitor from circuit
Disadvantages
 Expensive
 Complex assembly (busbars and fuses)
OPTION 3 - Electronic monitoring
Advantages
 May prevent serious failure by early shut down of
 Optional bank discharge mechanism to prevent
Disadvantages
 Must be designed into control circuitry
 Complex and expensive
Voltage Deration
If capacitors are operated at a voltage below their rated
value then the reduced stress and lower leakage current will
give an improvement in the life expectancy.
Since leakage current increases with temperature the
benefit of a reduced operating voltage is more pronounced
at higher temperatures. The graph below shows the voltage
deration factor (Kv) for products with a rated temperature
of 85°C and core temperatures (Tc) of 45°C, 65°C and 85°C.
equipment
capacitors dumping charge into failed capacitor
1.45
1.35
1.25
1.15
1.05
1.5
1.4
1.3
1.2
1.1
1
70
75
80
% of rated voltage
85
90
95
100
The life expectancy of a capacitor at full rated voltage is
multiplied by the voltage deration factor to obtain the new
life expectancy at the lower operating voltage:
Le
Le
Kv
Polarity and Reversed Voltage
Aluminium Electrolytic capacitors manufactured for use in
d.c. applications contain an anode foil and a cathode foil.
As such they are polarised devices and must be connected
with the +ve to the anode foil and the -ve to the cathode
foil. If this were to be reversed then the electrolytic process
that took place in forming the oxide layer on the anode
would be recreated in trying to form an oxide layer on the
cathode. In forming the cathode foil in this way heat would
be generated and gas given off within the capacitor usually
leading to catastrophic failure.
The cathode foil already possesses a thin stabilised oxide
layer, this thin oxide layer is equivalent to a forming voltage
of approximately 2V. As a result, the capacitor can withstand
a voltage reversal of up to 2V for short periods. Above this
voltage the formation process will commence.
Aluminium electrolytic capacitors can also be manufactured
for use in intermittent a.c. applications by using two anode
foils in place of one anode and one cathode.
Case Polarity - due to the presence of electrolyte in the
capacitor the aluminium can, stud mounting and any dummy
pins will essentially be at the same potential as the negative
terminal. BHC therefore recommend that they are either:
 left unconnected
 connected to the same potential as the negative
 insulated
Mounting
All aluminium electrolytic capacitors incorporate a safety
vent, in order to relieve build up of internal pressure due to
over stress or catastrophic failure. For the smaller ranges,
such as snap-in or solder pin types, this takes the form of a
weakened area in the side or base of the can. For the larger,
screw terminal types the vent is incorporated in the deck.
In all cases consideration must be given, when mounting
the capacitor, to the operation of the vent under failure
conditions. It is recommended that capacitors are always
mounted with the safety vent uppermost, or in the upper
part of the device. Should the vent operate the least amount
of electrolyte will then be expelled.
It is worth noting that screw terminal capacitors may be
mounted in any position so long as the vent can operate.
The operational and parametric performance is totally
unaffected by the physical orientation but should the vent
operate with the capacitor mounted upside down then a few
drops of electrolyte may be expelled.
(Vop)
(Vr)
terminal
- Life expectancy at operating voltage
- Life expectancy at rated voltage
- Voltage deration factor
Le
(Vop)
Application & Operation
= Le
Mounting continued overleaf....
(Vr)
x Kv
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