TTR 101 Vacuum Gauge Troubleshooting Guide

For KF flanges, use conductive metal clamping rings (instead of plastic rings) to ensure electrical continuity.

The single end of the cable shielding layer is grounded (through the connector housing), and the other end is suspended.

The power supply common terminal (GND) should be directly connected to the protective ground at the power source.

Use differential measurement input (separate wiring for signal ground and power supply ground).

The potential difference between the power supply ground and the casing is ≤ 18V (overvoltage protection).

3.3 Electrical Connection (8-pin FCC 68 connector)

Pin signal description

1 Power supply++14.5~30 V DC

2 Power Supply GND Common Terminal

3 measurement signals/SP1, SP2 0~10.23 V or threshold output

4 transmitter identification 71.5 k Ω to GND

5 signal public measurement signal return

6,8 Relay SP2 normally open contact (com)

7,8 Relay SP1 normally open contact (com)

Note: When the<SP1>or<SP2>button is pressed, the measurement signal output will be temporarily suppressed and replaced with the current set threshold voltage (for monitoring). This operation may cause the controller to malfunction, and it is necessary to confirm safety before operating.

Gas type correction

TTR 101 is independent of gas type and does not require correction within the range of 10~1500 mbar (capacitive sensor). In the low-pressure range dominated by Pirani (<1 mbar), the relationship between indicated pressure and actual pressure depends on the thermal conductivity of the gas.

The manual provides a calibration factor table (for transmitters calibrated for air):

Gas calibration factor C, actual pressure=C x indicated pressure

He 0.8 

H₂ 0.8 

Ne 1.4 

Air, O ₂, CO, N ₂ 1.0

Ar 1.7 

CO₂ 1.7 

Kr 2.4 

Water vapor 2.4

Xe 3.0 

Freon 12 3.0 

For example, when measuring argon gas (Ar), if the transmitter displays 1 × 10 ⁻³ mbar, the actual pressure is 1.7 × 10 ⁻³ mbar. When precise measurement of non air/nitrogen media is required, this correction must be applied.

Operation and Display

5.1 LED indicator light

<ST>(Status): Green=Measurement Mode; Red or flashing red=malfunction; Extinguish=no power supply.

<SP1>/<SP2>: Green=relay closed; Off=relay disconnected.

5.2 LCD display (with display model)

Display the pressure value (Scientific notation, such as 1.2E-3 mbar).

Display the set value in parameter mode.

The red display indicates an error.

5.3 Parameter Mode and Setpoint Adjustment

Press the<SP1>or<SP2>button (using a needle tool, diameter ≤ 1.1 mm), the transmitter enters the switch function mode, and the measurement signal output is temporarily replaced with the current threshold voltage. The LCD displays the threshold and flashes<S>. Press the same button again to change the threshold (increase upwards, long press to change direction). Release the button for more than 5 seconds, the new threshold will be saved and exited.

Warning: This operation will change the measurement signal output, and if the signal is used for process control, it may cause misoperation. Be sure to confirm safety before operating.

5.4 Switch characteristics

Low Trip Point (default): When the pressure is below the threshold, the relay closes and the LED lights up.

High Trip Point: The relay closes when the pressure exceeds the threshold.

Delay: 10% of the default threshold, which can be modified through Profibus programming.

Calibration and Adjustment

TTR 101 is calibrated at the factory. Long term use or pollution may cause zero drift, and it is recommended to regularly (such as annually) adjust the zero point.

6.1 Atmospheric pressure adjustment (ATM adjustment)

Install the transmitter on the vacuum system and run it on power for at least 10 minutes.

Ensure that the system is vented to atmosphere (pressure ≈ 1000 mbar).

Short press the<ADJ>button once with a needle. The Pirani sensor will be adjusted to 1000 mbar (default).

6.2 High Vacuum Adjustment

Extract the vacuum system to<10 ⁻⁵ mbar (pressure much lower than 5 × 10 ⁻⁵ mbar).

Wait for at least 2 minutes to stabilize the pressure.

Press the<ADJ>button with a needle (long press or specific operation, not clearly distinguished in the manual, usually the same button as ATM, identified by pressure). The transmitter automatically adjusts the zero point to 5 × 10 ⁻⁵ mbar.

If the output signal displays ≈ 4.85 × 10 ⁻⁵ mbar (or corresponding voltage), the adjustment is successful; Otherwise, repeat.

Attention: Before adjustment, it is necessary to ensure that the vacuum system has been pumped to extremely low pressure, otherwise it may introduce erroneous offset.

Troubleshooting

7.1 Common Problems and Countermeasures

Possible causes and solutions for the phenomenon

The output signal is always<0.1 V, and the<ST>red sensor cable is damaged or connected incorrectly; No power supply inspection cable; Measure the supply voltage

<ST>The red light is always on, but the output is normal. The transmitter is in an undefined state. Power off for 5 seconds and restart (reset)

<ST>The red light is always on, and the output is abnormal. Pirani sensor is damaged and replaced (see 7.2)