Watlow TLM-8 - Manual (Page 4)

4 WATLOW TLM-8 User’s Guide
Using the TLM-8
Sensor Types
Sensor types for the TLM-8 are factory configured; the
type of sensor for your TLM-8 is marked on the label.
Trip Points
Your TLM-8 has been factory configured with trip
points per your specification. Accuracy of a trip point
is ± 5% for TLM-8s with model numbers starting with
“TLME.” For example, 5% of a 200°C trip point is 10°.
So a 200°C trip point would trigger between 190 and
210°C.
Reading Trip Points
The trip points for TLM-8s with model numbers start-
ing with “TLME” are encoded in the part number. To
determine trip points from a part number, see the sec-
tion, TLM-8 Part Numbers. The trip points for TLM-8s
with model numbers starting with “TLMC” are listed
on the label.
Alarms and Acknowledgment
When the TLM-8 is powered and there is no alarm,
the alarm relay contacts are held closed. When a chan-
nel’s temperature exceeds the trip point or the sensor
fails, that channel’s indicator light is illuminated and
the global alarm relay contacts open.
When the TLM-8 is configured with the eight, optional
channel alarm relays and a channel’s temperature
exceeds its trip point, both the global alarm relay and
the corresponding channel alarm relay open.
All alarms are acknowledged with the ACK input. An
external device provides the logic signal to the ACK
input. The ACK input activates on the trailing edge of
the input signal. The input must be high for at least
20 milliseconds; when the input signal transitions to
low, alarms are acknowledged. Allow up to 3.5 seconds
after acknowledging the alarms for the relays to close.
Acknowledging alarms before the temperature drops
below the trip point or before a failed sensor is
repaired will have no effect. Wait until the tempera-
ture drops below the trip point before acknowledging
alarms. When the alarms are successfully acknowl-
edged, the alarm indicator lights turn off and the
alarm relay contacts close.
Reading the Indicator Lights
The alarm status of each channel is indicated by the
red indicator lights adjacent to the sensor input ter-
minal block. A channel indicator light turns on when
the associated channel goes into alarm. If the TLM-8
is configured with channel relays, this indicator light
reflects the status of the associated channel relay. The
indicator light will remain on until the acknowledge
input, ACK, is activated after the temperature drops
below the trip point.
The green power light indicates the TLM-8 has power.
SENSOR
J6
1
2
3
4
5
6
7
8
TST
-
V -
J5
ACK-
Channel 1
Channel 2
.
.
.
.
.
Channel 7
Channel 8
Power
Indicator
Lights
Alarm Status Indicator Lights
Testing the Outputs
The TLM-8 TST digital input allows users to simulate
excessive temperature on all channels. An external
device — switch or controller — provides the logic sig-
nal to the test, TST, input. All channels go into alarm
which can be easily verified by the channel indicator
lights. Use the following procedure to test the TLM-8:
1. Activate the TST input for at least 1 second. All
alarms and indicator lights should activate.
2. Deactivate the TST input.
3. Activate the ACK input for at least 20 millisec-
onds.
4. Deactivate the ACK input. All alarms should deac-
tivate within 3.5 seconds.
Changing Trip Points
To change a trip point on the TLM-8, obtain an RMA
number from your supplier and return the TLM-8 for
adjustment.
Maintenance
Over-temperature conditions may not occur regularly.
To test the TLM-8’s outputs, use the procedure in the
section “Testing the Outputs” to force the TLM-8 to
simulate alarm conditions on all channels.
To test trip point values and other system components,
use a thermocouple calibrator or other appropriate
means to simulate a sensor input above the trip point.