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6

305C Series

Vishay Cera-Mite

ceramite.support@vishay.com

Document Number: 23086

Revision 14-May-02

VISHAY

CERA-MITE

RESISTANCE (OHMS)

SWITCH TIME

CURRENT

MAX. VOLTAGE

AVG. POWER

COMPRESSOR

PART

CASE

(T) SECONDS

RATING

RATING

DISSIPATION

RANGE

NUMBER STYLE

± 20%

± 30%

@ 230V

AMPERES

VOLTS, RMS

WATTS

BTU (000)

HP

305C20*

C

25

35

0.25

10

410

3.5

10 - 28

0.75 - 2.0

305C21

C

35

50

0.35

8

410

3.5

8 - 18

0.5 - 1.5

305C22*

C

50

75

0.50

6

410

3.5

5 - 12

0..25 - 1.0

305C19*

B

20

30

0.50

18

500

7

20 - 50

1.5 - 4.0

305C12*

B

25

40

0.60

15

500

7

18 - 42

1.5 - 3.5

305C2

B

50

85

1.00

12

500

7

10 - 25

1.0 - 2.5

305C9*

A

10

15

0.50

36

500

9

28 - 68

3.0 - 7.0

305C11

A

12.5

20

0.60

30

500

9

28 - 62

3.0 - 6.0

305C1*

A

25

42.5

1.00

24

500

9

14 - 36

1.5 - 3.5

Note 1

Note 2

Note 3

Note 4

Note 5

Note 6

Note 7

PTCR Motor Start Packages

PTCR SELECTION

matter. See Table 4 and Table 2. Vishay Cera-Mite PTCRs

are available in three case sizes (A, B, and C).

Table 2 shows how to choose the correct resistance

value.

will give inadequate starting performance. An oversize

device will not harm the motor, but may not be optimum with

regards to acceleration dynamics, or power dissipation.

the voltage and current ratings.

Table 4

PTCR MOTOR START SELECTION CHART

Note 1

Part number is stamped on the device

for UL recognition. The customer

part number will also include 1 or

3 character alpha-numeric suffix to

designate mounting bracket, customer

marking, wire jumper, or other acces-

sory furnished.The suffix is not marked

on the part. Certified outline drawing

and complete part number will be

furnished on request for specific

applications. (Example: 305C19K01.)

Mounting brackets and other acces-

sories are shipped in separate boxes

to simplify installation in end use

equipment.

Note 2

R

when 230 volts, 60 Hz is applied (See

Fig T-7). This resistance determines

current and starting torque at the

moment of application of voltage to

the motor and can be measured with

an oscilloscope.

For receiving inspection or routine

trouble shooting, the D.C. resistance

(Ro) as measured with an ohmmeter

is approximately 50% greater. For

example: 305C20 measured with an

ohm meter would be 35 ohms ± 30%

tolerance.

Note 3

Resistance values are duplicated in

several case sizes (ie: 305C20, C12,

and C1) to provide longer switch time

(t) and higher current ratings (See

Fig T-7). Larger parts may be needed

for more difficult starting conditions

(voltage or temperature) or may be

used for accelerating fans against

back pressure.

Note 4

Maximum current in the PTCR is

determined by

Max Line Voltage

Min R

DYN

Motor auxiliary winding impedance

is usually small compared to PTCR

resistance, and does not materially

affect PTCR current.

Current in PTCR is a percentage of

the full motor inrush (locked rotor)

current; usually 30% to 50% (See

Fig T-5).

Note 5

In application, the maximum voltage is

the voltage that appears across the

run capacitor at rated speed, high line,

light load. This is not the applied line

voltage (See Fig T-6).

THESE DEVICES ARE INTENDED

FOR APPLICATION ON 240 VOLT

LINES OR SYSTEMS WITH MAXI-

MUM LINE VOLTAGE UP TO 264

VOLTS. The 305C20, 21 and 22 are

also used on 120 volt systems where

the motor is designed to use same

run capacitor and PTCR as equivalent

230 volt compressor.

Note 6

This is the power used to keep the

PTCR switched off under full load

running conditions at typical ambient

temperature.

Note 7

BTU and horsepower ranges are

for reference only. PTCR may be

applied outside those ranges as long

as maximum voltage and maximum

current are not exceeded. Scroll

and rotary compressors may require

less starting assistance allowing use

of smaller devices.

* Preferred Values