WELD SENTRY 2
Page 33
SECTION 4 - SPECIFICATIONS
VOLTAGE INPUTS
The Weld Voltage measurement range is 0.10 to 40 volts peak. The pickup cable (4-32409-01) is a 7 foot
(2.1 m) shielded cable assembly with a 3-pin plug (520-110) on one end which mates with a 3-pin
receptacle (550-070) mounted on the rear panel of the Sentry. The two pickup leads end in alligator clips,
black for negative and red for positive.
CURRENT INPUTS
The Weld Current measurement range is 15 to 100,000 amps peak depending on the type of current pickup
which is used. Current can be measured using either a magnetic induction current coil or a user-supplied
current shunt.
CURRENT COIL - The current coil has a 6 foot (l.8m) cable with a 2-pin plug (520-1-109) on one end
which plugs into a 2-pin receptacle (550-1-069) mounted on the rear panel of the Sentry. The Weld
Sentry is supplied with a 1x current coil (10-309-01) with a current measurement range of 150 to
100,000 peak Amps. A 10x current coil (10-310-01) is available which is 10 times more sensitive and
has a current measurement range of 15 to 10,000 peak Amps.
CURRENT SHUNT - A user-supplied current shunt can be connected directly in series with the weld
current path. The voltage caused by the weld current passing through the shunt is measured using the
Current Shunt Pick Up Cable (32410-01) provided with the Weld Sentry. The shunt resistance values
which can be used with the Sentry are: 10, 1, 0.1 and 0.01 milliohms. The corresponding voltage input
range is 0.10 to 40 volts peak. The current measurement is calculated by the Sentry using the voltage
measurement and the resistance value of the shunt (I=V+R). Theoretically, up to 400,00A could be
measured, however, due to power losses this would not be practical. A current shunt will cause
additional resistance in the weld loop which should be kept as small as possible. If there are excessive
variations in resistance due to cable or shunt heating, the monitoring process will be ineffective.
TRIGGER INPUTS
The Weld Sentry can be setup to start the monitoring process on either the Weld Voltage or the Weld
Current. The signal required to trigger the process is between 5% and 10% of full scale relative to the gain
setting used. It is possible for a "false" trigger to occur due to transient voltage in the weld loop or
inductance caused by other equipment. During Basic Setup the Weld Sentry checks the inputs and
automatically sets the optimum Trigger. For electrically “noisy” environments a Start Signal should be
used.
START SIGNAL
The start signal is an additional input which is used to signal the Sentry to expect a trigger signal
momentarily. The Sentry remains on “Standby” ignoring all signals until the Start Signal is recognized.
The Sentry can be programmed for a dry contact closure (open or closed) or a + 5V logic level (high or
low). The cable used is an optional accessory, catalog number WSTC (10-308-01) which plugs into the rear
panel of the Sentry.
MEASUREMENT ACCURACY
The voltage and current signals are measured using a microprocessor based 8 bit, analog-to-digital
converter. The absolute accuracy of the measurements is 2% of reading, with a minimum of ± 0.5% of full
scale for the specific selected measurement range. The repeatability is better than ± 0.5% of full scale for
the specific selected measurement range.
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