Basic Installation and Operation Guide VMX Series Digital Solid State Soft Starters 18 – 1000A
Page 14 of 27
PTC Thermistor Input
The
VMX 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 resistance as the temperature
increases. When the
VMX Series
detects that the PTC input
resistance is too high, it initiates a PTC trip, and displays it on the
readout as
[ PTc]
. 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 terminals are located on TB1, Terminals 9
and 10.
Resistance must be less than or equal to 750
Ω
at 25ºC. If multiple
resistors are used in the motor, the sum of all resistors in series
must equal or be under this value.
Fault Signal
An optically isolated Triac output is dedicated as a fault indicator on TB1, terminals 11 and 12. The output Triac
switch is rated for 10 - 250 VAC/DC,
50 mA (maximum)
. If the three programmable Output Auxiliary Relays are
being used for other functions, this output can easily be hooked up
to a PLC or small external relay to provide a Fault signal. This Fault
Output operation is permanently fixed at “Any Trip”, duplicating the
Relay setting #16 as shown in Table 5.6.10.
This output is permanently set to this function and is not
programmable.
Dual Ramp and Jog Features
TB1 includes provisions for enabling the Dual Ramp and Jog functions by using external contact closures. Both
features use a 24VDC from Terminal # 7, however they can be used independently of each other or
together. See sections 5.6.2 and 5.6.3 of the Advanced Installation,
Operation and Programming Manual for full function descriptions and
setup.
+
N C
JOG
RAMP2
PTC
OPTO
Figure 9:
PTC Resistor Connection
TB-1
PTC Resistor in M otor
9 10
**
** Remov e factory jumper
from Terminals 9 and 10
N C
JOG
RAMP2
PTC
OPTO
Figure 10:
Fault Output Opto-Triac Connection
TB-1
11 12
External Fault Re lay
or PLC Input
R
Control Powe r or PLC Source
N C
JOG
RAMP2
PTC
OPTO
Figure 11:
Dual Ramp / Jog Connections
TB-1
RAM P 1 RAMP 2
RUN JOG
6 7 8
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