12
installation
&
operation
manual
|
oxm
/
ogm
heating
system
5.2.10 TEMPERATURE CONTROL RELAY
(TCR)
WARNING
!
Hazardous voltage:
Before wiring, servicing or cleaning
the heating system, turn off the power and follow your
organization’s lockout and tagout procedure. Failure
to do so could allow others to turn on the power
unexpectedly, resulting in harmful or fatal electrical
shock.
If the OXM/OGM heating system does not maintain the
desired preset control temperature or signals a high-limit
temperature fault immediately upon system start-up,
the TCR (temperature control relay), the RTD (resistance
temperature device), or the RTD cable may require
replacement. To perform this troubleshooting, you
will need:
•
Ohmmeter
1.
De-energize the heating system. Verify fluid
is present and flow is not restricted. Check
temperature gauge to ensure the liquid in the tank
is below 122 °F (50 °C).
2.
Verify the control TCR is set correctly. Verify that
high-limit TCR is set at least 18 °F (10 °C) higher
than the control TCR set point.
3.
Using the ohmmeter, measure the resistance
between TCR terminals
O1
and
O2
(See Fig. 9)
:
h
If the measured resistance is
between 80 and
120 ohms
continue troubleshooting.
Proceed
to step 4.
h
If the resistance is
lower than 80 ohms
or
higher than 120 ohms
,contact HOTSTART
for further assistance.
4.
Using the ohmmeter, test for continuity between
TCR terminals
O2
and
O3
:
h
If there
is continuity
between TCR terminals
O2
and
O3
, the TCR, RTD and RTD cable are
functioning correctly. Close control panel.
Allow fluid to cool below high-limit preset
temperature. Perform system start-up
(see
SECOIO 4
)
. If fault or temperature problems
persist after start-up, contact HOTSTART for
further assistance.
h
If there
is no continuity
between TCR terminals
O2
and
O3
, locate connected RTD on the
heating tank. Unscrew the RTD plug from RTD.
See Table 2 and Fig. 10, Fig. 11
on following
page.
5.
Using the ohmmeter, touch the probes to RTD
pin 1
and
pin 3
.
See Fig. 10.
Note the resistance.
Touch the probes to RTD
pin 1
and
pin 4
to check
for continuity:
h
If the resistance between RTD
pin 1
and
pin 3
is
between 80 and 120 ohms
and there
is continuity
between RTD
pin 1
and
pin 4
, the
RTD is functioning properly. Replace the
RTD cable.
h
If the resistance between RTD
pin 1
and
pin 3
is
not between 80 and 120 ohms
or there is
no continuity between pin 1
and
pin 4
, the
RTD is malfunctioning. Replace the RTD.
See
SECOIO 5.2.11
PIN 1
(BROWN
WIRE)
PIN 3
(BLUE
WIRE)
PIN 4
(BLACK
WIRE)
A
B
CN ORNL
HIGH
LIMIO
TCR
TYPE
RTD Position
TCR1
Oil
Control
40 °C
Tank Inlet
TCR2
Oil
High-limit
90 °C
Tank Outlet
Table 2. TCR types, default temperature settings and
corresponding RTD positions.
Figure 9. Control (TCR1) and
high-limit (TCR2) TCR showing
terminals T1, T2 and T3.
Figure 10. RTD pins 1, 3 and 4. The resistance
between pin 1 and pin 3 should measure between
80 and 120 ohms. There should be continuity
between pin 1 and pin 4.
