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Global Power Technologies
6720 VOLTAGE LIMITER FOR MODEL 8550-RU TEG
302954 rev0 | Model 8550-RU
Page 45 of 53
8.2.2
VOLTAGE SENSING RELAY ADJUSTMENT
The user-adjustable Voltage Sensing Relay allows the customer to monitor the status of the Model
8550-RU TEG. When the VSR is de-energized, the Common (COM) terminal is connected to the
Normally Closed (NC) contact. When the VSR becomes energized, the Common terminal is instead
connected to the Normally Open (NO) contact.
From the factory, the Model 8550-RU TEG VSR will be set so that the VSR will energize when the
power unit voltage climbs above 23 Volts. The VSR also incorporates approximately 0.5 Volts of
hysteresis, meaning once the VSR is energized the voltage would need to drop 0.5 Volts below the
energize threshold for it to de-energize (22.5 Volts factory default).
The VSR contacts can be easily used to generate Low-Voltage-Alarm or Voltage-Good signals for
customer equipment with the factory default 23 Volt VSR setpoint. For example, a connection
between the COM and NC terminals indicates the voltage is below standard operating voltage,
indicating a Low-Voltage-Alarm. Conversely, if a connection is observed between the COM and NO
terminals, then the voltage is confirmed to be above the VSR threshold, indicating a Voltage-Good
status.
The VSR energize threshold can be adjusted with the following procedure:
1.
Ensure the TEG has been running for at least an hour to stabilize.
2.
Disconnect all customer load connections from terminals 2 and 4 of TB-1.
3.
Connect a voltmeter across terminal 2 (+) and terminal 4 (-) of TB-1.
4.
Connect a multimeter across the COM (+) and NC (-) terminals of the VSR & Control Board within
the 6720 Limiter. Set the multimeter to measure continuity (or resistance).
5.
Using a small flat blade screwdriver, adjust the Voltage Adjustment Screw on the 6720 Limiter
until the voltmeter reads your desired VSR energizing voltage.
6.
Carefully adjust the Voltage Sensing Relay Adjustment Screw on the 6720 Limiter until the VSR
energizes, as evidenced by the multimeter detecting continuity (under 1 Ohm) between the COM
& NC terminals. You want to stop turning the screw the moment continuity changes. If you
overshoot by too much, adjust the screw in the opposite direction until the VSR deenergizes,
then try again.
7.
Re-adjust the Voltage Adjustment Screw to return the customer output voltage to its proper
setpoint.
8.
Remove both meters and reconnect your customer load connections.
8.3
SERVICE
The all-solid-state high-reliability design of the Voltage Limiter renders it nearly maintenance free.
Check for the following during the annual maintenance:
1.
Obstruction of air flow through the heat sink area.
2.
Output voltage level is correct. Reset, if necessary. S
ee Section 4.1.3.
3.
Tighten the wire connections at input and output of the power conditioner. Look for oxidized
high resistance contacts. If any exist, clean and re-tighten.
Содержание 8550-RU
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