Basic Installation and Operation Guide
TE Series Digital Solid State Soft Starters 18 – 1250A
20 |
P a g e
4.2.6 PTC Thermistor Input
The
TE Series
starter is provided with input terminals for connecting a
PTC (Positive Temperature Coefficient) Thermistor that may be
imbedded in the motor. These are specialized resistors imbedded in
some motor windings that increase in resistance as the temperature
increases. When the
TE Series
detects that the PTC input resistance is
too high, it initiates a PTC trip, and displays
[PTc]
on the readout. This is
independent of the Thermal Register overload current protection and
provides supplemental protection for high motor ambient temperature
applications. Terminals for this input are provided with a factory jumper
that must be removed if the PTC input is used. These are Terminals 9
and 10 located on TB1.
PTC resistors are also found in other devices such as bearings, air
receivers, oil or coolant reservoirs and air discharge systems that may
require shutdown of the motor.
PTC Resistor Values:
The resistance must be greater than or equal to 750
at 25ºC. If
multiple resistors are used in the motor, the sum of all resistors in series
must equal or exceed this value.
4.2.6.a
External Overload Relay Connection
If an external Overload Relay (OLR) is used (see Section 3.1.3.c and
Appendix 4), connect the NC aux. contact of the OLR to the PTC
input after removing the jumper. When the external OLR trips, the
contact will open, opening the resistance input to the PTC circuit (the
resistance goes to infinity). This indicates an immediate Over Load to
the starter, which trips and displays
[PTc]
on the readout to
differentiate from the internal Thermal Overload trip. If multiple OLRs
are used, i.e. multiple motors controlled by the same
TE Series
starter, simply wire the Aux Contacts in series as shown in Figure
4.2.6.a. See Appendix 4 for additional information.
Note:
An Emergency Stop Push Button or any other field device may be
wired to the PTC input using NC contacts. When the contacts open,
the starter will detect it as a PTC trip. Even if a PTC is used in the
motor, field devices can still be added as long as the total circuit
resistance is not exceeded.
This feature is especially useful when using Decel Control because it
will immediately shut off power to the motor even if Decel is active. If
used this way, instruct the users as to the trip indication issues (i.e.
the display will show
[PTc]
and the Overload LED will be on).
+
N C
JOG
RAMP2
PTC
OPTO
Figure 4.2.6:
PTC Resistor Connection
TB-1
PTC Resistor in Motor
9 10
**
** Remove factory jumper
from Te rminals 9 and 10
N C
JOG
RAMP2
PTC
OPTO
Figure 4.2.6.a:
External Overload Relay(s)
and/or E-Stop PB Connection
TB-1
External OL Relays
OLR 1 OLR 2
9 10
Optional
Emergency Stop PB
**
** Remove factory jumper
from Terminals 9 and 10
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