General Maintenance - Acromag 461A Series User Manual

Ac-powered alarm

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Series 461A User's Manual

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4. After programming the jumpers, install the alarm circuit boards

back into their case as described in the assembly procedure

below.

Assembly Procedure for the 461A Plastic Housing:

1. Refer to drawing 4501-545 and line up the left plastic side with

the board and terminal assembly. Carefully press the pieces

together.

2. Align the pins of the center section with the side and press the

pieces together.

3. Now line up the right side of the housing with the left side and

center assembly and carefully press the pieces together.

Alarm - Adjustment Procedure:

Connect the alarm as shown in Calibration Connection Drawing

4501-543. For best results, the input source must be adjustable

over the entire range of the unit and settable to an accuray of 0.1%

or better. The alarm status LED's can be used to indicate relay

action. The RED LED will turn ON when the relay changes state

from a non-alarm to an alarm condition, at the same time the

GREEN LED will turn OFF.

The setpoint and deadband potentiometers are accessible from

the front panel of the alarm (refer to Drawing 4501-543). The

screwdriver blade used to adjust the potentiometers should not be

more than 0.1 inch (2.54mm) wide.

Alarm - Calibration Example:

MODEL:

461A-V1-SMRN-1-DIN-NCR (Single Alarm)

Input:

4 to 20mA - Install a jumper between the Input (+)

and Input (L) terminals for current input.

Setpoint:

12mA

Alarm Action:

High (HI) Alarm

Alarm Type:

Failsafe

Output:

DPDT Relay Contacts

A. Adjustment Procedure (High and Low Alarms):

Notes (Adjustment Procedure):

1. The adjustment procedure is similar for other inputs.

2. The adjustment procedure is the the same for both Failsafe and

Non-Failsafe operation.

3. When the RED LED is ON, it indicates an alarm condition for

both the Failsafe and Non-Failsafe mode of operation. The

GREEN LED is ON when the signal is in the Normal operating

range.

4. If unit is a dual alarm (-DMRN models), repeat this procedure for

the second channel using the SP2 and DB2 adjustments

(SetPoint 2 and DeadBand 2).

5. Noise and/or jitter on the input signal has the effect of reducing

(narrowing) the instrument's deadband and may produce

contact chatter. To reduce this undesired effect, increase the

deadband setting.

HIGH ALARMS:

1. Set the deadband adjustment pot DB1 fully counter-clockwise for

minimum deadband (approximately 0.5% for a pure DC signal).

2. Adjust the input source for 12.000mA DC (value desired for

alarm setting in this example).

3. For High Alarms, turn the setpoint potentiometer (SP1)

clockwise, just until the relay changes states and the RED LED

turns OFF. If the RED LED is already off, proceed to step 4.

4. Now, turn the setpoint potentiometer (SP1) counter-clockwise

very slowly, just until the relay changes states and the alarm

RED LED turns ON. The setpoint is now calibrated. Check

your calibration as noted in step 5 below.

5. For High Alarms, check the setpoint by reducing the input

current until the relay changes states and the alarm RED LED

turns OFF. Then slowly increase the input current until the

alarm just trips (RED LED turns ON). The input current should

be within ±0.1% (±0.016mA) of the desired trip point. If not,

perform steps 1 through 4 again.

6. If increased deadband is required, turn DB1 control clockwise.

Vary the input signal near the trip point and determine the input

values for pull-in and drop-out of the relay. The difference

between these values is the amount of deadband. Note that

readjusting the deadband potentiometer does not affect the

setpoint adjustment.

LOW ALARMS:

1. Set the deadband adjustment pot DB1 fully counter-clockwise for

minimum deadband (approximately 0.5% for a pure DC signal).

2. Adjust the input source for 12.000mA DC (value desired for

alarm setting in this example).

3. For LOW Alarms, turn the setpoint pot (SP1) counter-clockwise

until the relay changes state and the RED LED turns OFF.

4. Now, turn the setpoint potentiometer (SP1) clockwise very

slowly, just until the relay changes states and the RED LED

turns ON. The setpoint is now calibrated. Check your

calibration as noted in step 5 below.

5. For LOW Alarms, check the setpoint by raising the input current

until the relay changes states and the RED alarm LED turns

OFF. Then slowly decrease the input current until the alarm just

trips (RED LED turns ON). The input current should be within

±0.1% (±0.016mA) of the desired trip point. If not, perform

steps 1 through 4 again.

6. If increased deadband is required, turn DB1 control clockwise.

Vary the input signal near the trip point and determine the input

values for the pull-in and drop-out of the relay. The difference

between these values is the amount of deadband. Note that

readjusting the deadband potentiometer does not affect the

setpoint adjustment.

NOTE: Optionally, the setpoint may be adjusted by connecting

a DVM to the setpoint voltage testpoints on the front of the

alarm. The voltage measured here is 0 to 5V, corresponding to

0 to 100% of input voltage span. For current inputs, a setpoint

voltage of 1 to 5V corresponds to 4 to 20mA of input current.

This setpoint voltage represents the true setpoint to within 1% of

input span and is a more convenient method of setpoint

adjustment where high precision is not required. These test

points will accept up to an 0.080 inch diameter probe tip (do not

insert probe tip more than 0.4 inches deep).