The ActionI/Q model Q520 is a DIN rail mount, thermocouple input, dual (2) channel, two-wire transmitter. Each channel accepts a thermocouple input and provides an isolated, 4-20mA output signal, linear to the millivolt input. Cold junction compensation is provided and each channel is fully isolated (1800VDC) from input to output and channel to channel.

All ActionI/Q modules feature SnapLoc, plug-in, screw terminals for easy installation and low Mean-Time- To-Repair (MTTR). If desired, two or more modules can slide together and interlock for solid, high density mounting. This is accomplished by removing either the foot, or the adjacent unit's face plate, for right-hand side or left-hand side monting, respectively. The module to be attached will easily slide on to the side of the mounted unit.

Application

Thermocouple input, two-wire transmitters are used to convert a specific temperature range into a regulated 4-20mA signal. Two-wire transmitters are primarily used in remote locations near the sensor since they reduce the probability of signal errors and save wiring costs by utilizing the two power wires to send the 4-20mA signal. The current signal is usually monitored by a control system or data recorder.

Typically, thermocouples are used to measure high temperatures such as in an oven or furnace. Thermocouple wires can be run a short distance to a panel, or farther with the use of shielded wire, without errors caused by noise or lead resistance in the wires. These sensor wires are usually terminated at the two-wire transmitter and converted into a 4-20mA signal which is highly immune to noise and not affected by lead resistance, both of which can cause significant errors (1mV @ 25°C) in voltage signals transmitted over long distances.

Operation

The ActionI/Q model Q520 operates as a two-wire transmitter; each channel derives its power from a (12-35VDC) source connected in series with the 4-20mA output loop. Typically a 24VDC source is used for power, allowing 12VDC (600W @ 20mA) for other devices connected in series, in the current loop. The outputs of the Q520 are isolated from the inputs and protected from reverse polarity. Zero and span pots are provided for each channel.

Input     

• Types: Accepts two J, K or T Type thermocouples 
• Ranges: see Table 1
  

Burnout Detection   

• Upscale standard;
• Downscale, option B
  

Cold-Junction Compensation Error   

1°C typical, 0 to 80°C ambient; 3°C typical, -40 to 0°C ambient

Output Range   

4-20mA

Supply Voltage Range   

12 to 35VDC, each channel

Output Accuracy   

< 0.1% of full-scale input (mV) typical, < 0.2% maximum @23°C including linearity, repeatability and hysteresis (not including CJC error)

Adjustability     

Front accessed 10 turn, + 5% of span for zero and span

Stability   

< 0.025%/°C of full-scale maximum for full-scale and zero