Guralp Systems Limited
MAN-030-0001 - Güralp 3T Operator's guide

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1. Preliminary Notes 2. Introduction 3. Installing the 3T 4. Calibrating the 3T 5. Accessories 6. Inside the 3T 7. Connector pin-outs 8. Specifications 9. Revision history

Section Index: 5.1. The breakout box 5.2. The hand-held control unit 5.3. Integrated State-of-Health Controller

Chapter 5. Accessories

5.1 The breakout box

This unit separates the lines in the signal cable, so you can connect a power supply, a recording system, and the hand-held control unit:

You can also use the breakout box to centre, lock and unlock the sensor masses. You will need to provide power through the breakout box's POWER connector to do this (see below.)

For more details on the control system, see Section 6.2.

The standard breakout box is rain resistant but not waterproof. If you intend to use a breakout box in your installation, you should site it away from potential flooding. If this is not possible, a larger unit is optionally available which can be immersed in water. (The 3T itself is, however, completely waterproof.)

5.2 The hand-held control unit

This portable control unit provides easy access to the seismometer's control commands, as well as displaying the output velocity and mass position (i.e. acceleration) on an analogue meter. It takes input from the 26-pin connector at the bottom, and repeats it at the connector on the side for connection to further equipment.

The hand-held control unit can be sited up to fifty metres from the breakout box.

5.2.1 The meter

The meter at the top of the unit allows you to monitor the voltage outputs of the instrument. You can use the knob below to select, for each of the three components, either the mass position output or the velocity output. There is also a RANGE switch allowing you to alter the sensitivity of the meter.

5.2.2 Calibration

The hand-held control unit can be used to calibrate the 3T. To activate the calibration relays, turn the knob to the component you wish to calibrate, and introduce a calibration signal on the CAL SIG banana sockets.

5.2.3 Control commands

You can use the hand-held control unit to centre, lock and unlock the sensor masses.

Note: The ENABLE, LOCK, CENTRE and UNLOCK switches require only a single quick press to initiate the processes. Do not hold them down.

For more details on the control system, see Section 6.2.

5.2.4 Outputs

The remaining banana sockets provide easy access to the output voltages of the instrument. For each component (vertical, N/S and E/W):

Ground references for each of these voltages are provided at the bottom of the unit. Ensure that you do not connect either side of a differential output to ground.

5.3 Integrated State-of-Health Controller

The CMG-3TD variant (a CMG-3T with an integrated DM24 digitiser) is available with an optional, in-built state-of-health controller.

This option provides a simple means to centre, lock and unlock the masses without the need for a hand-held control unit.

The lid of the device is fitted with four momentary, colour-coded push-buttons, labelled “ENABLE” (black), “CENTRE” (blue), “UNLOCK” (green) and “LOCK” (red) - together with a red LED, labelled “BUSY”.

These buttons are used in a similar manner to those on the break-out box with the exception that it is not necessary to hold the buttons down for seven seconds - one second is adequate.

For more details on the mass control system, see Section 6.2.

PreviousNext

1. Preliminary Notes 2. Introduction 3. Installing the 3T 4. Calibrating the 3T 5. Accessories 6. Inside the 3T 7. Connector pin-outs 8. Specifications 9. Revision history