PTC305C Series

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Vishay Cera-Mite

Revision: 11-Sep-15

7

Document Number: 23086

THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT

VISHAY CERA-MITE MOTOR START FEATURES

ADVANCED CERAMIC ENGINEERING FOR HVAC

Vishay Cera-Mite’s capability in large diameter ceramic

pellets, unique formulations tailored to motor starting, and

heavy duty electrode systems, have been developed and

proven with the cooperation of HVAC industry experts over

a period of more than 30 years.

INHERENT PERFORMANCE

Large diameter pellets make possible low resistance start

devices needed to match torque requirements of high

efficiency compressor motors.

Various package sizes offer selection of timing intervals,

providing optimum switching time without dependence on

sensing speed, counter EMF, or current.

RUGGED MECHANICAL CONSTRUCTION

Vishay Cera-Mite PTC cases are molded from a UL 94 V-0

high temperature, engineered plastic/glass composite.

Heavy duty aluminum contact plates and stainless steel

force springs are scaled to the pellet sizes and current

ratings to insure no internal arcing and to enhance quick

reset time.

Unbreakable metal mounting brackets, sold separately,

attach securely with a single screw. The “U” - brackets

developed by Vishay Cera-Mite feature lower power

consumption and greater reliability by maximizing case to

ground thermal impedance.

SIMPLE AND ECONOMICAL

A solid state device requiring only 2 quick connect wires and

one bracket screw to install. Compared to the alternative

start capacitor and relay, PTC start devices save several

wires, occupy less panel space, mount more easily, and

cost less.

OUTSTANDING RELIABILITY

Over a twenty year period, with an installed base of millions

of Vishay Cera-Mite PTC start devices, experience has

demonstrated reliability at 1.0 FIT or less. Users have

benefited from very low warranty expense.

RESTART CONSIDERATIONS

A properly sized PTC will provide adequate starting current and starting time with a cool down time of 3 min to 5 min,

coordinating perfectly with standard “off delay” equalization timers restart characteristics of the three case sizes are shown.

Fig T-13

Fig T-14

Fig T-15

25

% Initial

Current

50

75

100

0

0

0.2

0.4

0.6

0.8

5 Min Coolin g

3 Min

Cooling

Cold

Start

0

0.2

0.4

0.6

0.8

1.0

5 Min Cooling

3 Min

Cooling

Cold

Start

25

50

75

100

0

0

0.2

0.4

0.6

0.8

1.0

25

50

75

100

0

1.2

Cold

Start

3 Min

Cooling

5 Min Cooling

Time (s)

Time (s)

Time (s)

CASE STYLE C

CASE STYLE B

CASE STYLE A