PTC305C Series
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Vishay Cera-Mite
PTC Thermistors Motor Start Packages
FEATURES
Large diameter ceramic pellets for high starting
current
Various package sizes for optimum inrush
current and switching time
Rugged mechanical construction for reliable long life
operation
UL approved packages
Plastic case mold UL 94 V-0 approved
Adapted accessories for easy mounting
Material categorization: for definitions of compliance
please see www.vishay.com/doc?99912
QUICK REFERENCE DATA
PARAMETER VALUE UNIT
APPLICATIONS
Resistance value at 25 C 15 to 75
Single phase motor start assist in
Tolerance on resistance value 30 %
- Refrigerator systems
Maximum current ratings 6 to 36 A
RMS
- Air-conditioning systems
Switching temperature 110 to 120 C
- Heat-pumps
Switching times (typical) 0.25 to 1.0 s
- Small compressors
Maximum voltage rating 410, 500 V
RMS
Operating temperature range -10 to +80 C
Storage temperature range -25 to +105 C
PTC MOTOR START SELECTION CHART
MAX.
SWITCH CURRENT COMPRESSOR COMPRESSOR
VISHAY CERA-MITE CASE R () R ( ) VOLTAGE
DYN 25
TIME RATING RANGE RANGE
PART NUMBER STYLE 20 % 30 % RATING
t (s) at 230 V (A ) (BTU 000) (HP)
RMS
(V )
RMS
PTC305C20 C 25 35 0.25 10 410 10 to 28 0.75 to 2.0
PTC305C21 C 35 50 0.35 8 410 8 to 18 0.5 to 1.5
PTC305C22 C 50 75 0.50 6 410 5 to 12 0.25 to 1.0
PTC305C19 B 20 30 0.50 18 500 20 to 50 1.5 to 4.0
PTC305C12 B 25 40 0.60 15 500 18 to 42 1.5 to 3.5
PTC305C2 B 50 85 1.00 12 500 10 to 25 1.0 to 2.5
PTC305C9 A 10 15 0.50 36 500 28 to 68 3.0 to 7.0
PTC305C11 A 12.5 20 0.60 30 500 28 to 62 3.0 to 6.0
PTC305C1 A 25 42.5 1.00 24 500 14 to 36 1.5 to 3.5
PTC MOTOR START ACCESSORY SELECTION CHART
ACCESSORY
DESCRIPTION
PART NUMBER
PTCAUX36-520M Round mounting bracket for case style C
PTCAUX36-520H Round mounting bracket for case style A and B
PTCAUX7-36-5C U-shaped mounting bracket for case style B
PTCAUX7-36-4C U-shaped mounting bracket for case style A
PTCAUX50-1278 Jumper wire for case style A
Revision: 11-Sep-15 Document Number: 23086
1
For technical questions, contact: ceramitesupport@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
PTC305C Series
www.vishay.com
Vishay Cera-Mite
ECONOMICAL SOLID STATE TORQUE ASSIST FOR HEAT PUMPS, ROOM AIR, COMMERCIAL AND
RESIDENTIAL AIR CONDITIONING AND REFRIGERATION SYSTEMS
Positive Temperature Coefficient Themistors (PTC) have Safety Agency Recognition
been used for many years in millions of HVAC applications
Vishay Cera-Mite motor start PTC thermistors are
to provide starting torque assistance to Permanent Split
recognized by Underwriter Laboratories file E97640 in
Capacitor (PSC) single phase compressor motors.
accordance with standard for controllers and refrigeration
Sizes are available to cover the full range of 120 V/240 V components UL 873 or UL 60730; and Canadian Standard
PSC compressor motors. C22.2 No. 24. All packages and accessories are
RoHS-compliant.
RELATIVE COMPARISON OF VARIOUS MOTOR STARTING METHODS
Three methods have historically been employed to generate The importance of each category is dependent upon the
motor application and industry sector.
starting torque for PSC motors. All are well-proven
technologies and may be compared relative to one another In general, if the PTC starter produces sufficient starting
based upon categories shown below. torque, it is considered the simplest and most economical
choice.
Table 1
MECHANICAL ELECTRICAL FINANCIAL
SENSITIVE
STARTING
EASE PANEL ACCELERATION ACCELERATION RESET INVENTORY
TO EMI/RFI PURCHASED
METHOD
OF SPACE TORQUE (SWITCH) TIME TECHNOLOGY MIX RELIABILITY
MOUNTING GENERATED COST
WIRING REQUIRED PRODUCED TIME REQUIRED REQUIRED
DIRECTION
Simple 3 min to
PTC starter Lowest No Lowest Fixed No Solid State Lowest Highest Lowest
2 wire 5 min
Start cap
Moderate
with PTC 2 min to
2 wire or Medium Yes Medium Fixed No Solid State Medium Medium Medium
acting as a 5 min
3 wire
current relay
Start cap
Difficult Variable
used with Electro
4 wire or Highest Yes Highest based on None Yes Highest Lowest Highest
potential or Mechanical
5 wire motor speed
current relay
SIMPLIFIED PTC STARTING DIAGRAM
Start Sequence Restart
When starting the compressor, contactor (M) closes; the It is important to provide time between motor starts to allow
PTC, which is at low resistance, provides starting current to the PTC to cool to near its initial temperature. This time is
the motors auxiliary winding. After time delay (t), the current usually 3 min to 5 min and is determined by the thermostat
passing through the PTC causes it to heat and switch to a (THERM) or separate time-delay relay (TR). Attempts to
very high resistance. At this point the motor is up to speed restart in less time may be successful depending on
and the run capacitor (C ) determines the current in the compressor equalization, line voltage, temperature, and
R
auxiliary winding. The PTC remains hot and at high other conditions. If the motor were to stall in a locked-rotor
resistance as long as voltage remains on the circuit. When state, overload device (PD or TS) would open the line and a
contactor (M) opens, shutting off voltage to the compressor, further time delay would occur until the motor overload is
the PTC cools to its initial low resistance and is again ready reset. Motor start PTCs are applied to compressors having
to provide torque assist on the next startup. means to equalize pressure during shutdown.
TYPICAL PTC CHARACTERISTICS
Fig T-2
AS A MOTOR START DEVICE
L
PD
1
M Fig T-3
PSC
Protective
T TS
HERM
MOTOR
Device CURRENT
10 000 10.0
Internal
MAIN
Motor
TR
Winding
M
Overtemp
AC Line 1000 1.0
Switch
Optional OFF
120 or 240
Time Delay
TR C
VOLTS AC R AUX.
Relay
M
100 Switch Time (t) 0.1
Protective
PTC RESISTANCE
Device M
L
2
Low Voltage Control Transformers Not Shown 10 0.01
50 100 150
PTC Temperature C
Revision: 11-Sep-15 Document Number: 23086
2
For technical questions, contact: ceramitesupport@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
PTC Resistance ()
PTC Current (A )
RMS