IMR01M01-E16
19
Continued from the previous page.
Constant current control
This is the function used to keep the output current constant in proportion to the input signal. This function is effective when a
heater with large resistance changes caused by temperature variations is used (such as tantalum, superkanthal, tungsten,
platinum, or molybdenum). The maximum output current when the Constant current control function is used coincides with the
rated current in the thyristor specification.
Operating condition Stability
Power supply voltage variation ±10 %
±2 % of full scale
Load variation 2 times
Caution for using Constant current control function
If the rated current of thyristor differs from that maximum load current flowing through the heater, compensate for the
difference by setting the gradient. If there is the difference, a section where control is disabled may come into existence.
A compensation example when there is a difference between the currents flowing through the thyristor and the heater is
shown in the following.
Example: When used in the following condition
• Rated current of Thyristor: 30 A • Input signal from controller: 4 to 20 mA DC
• Maximum load current of heater: 15 A • Soft-start time setting: 0.0 seconds
The Soft-start function is activated during four cycles from load operation start even at a Soft-start time of 0.0 seconds.
When used without setting the gradient, the maximum heater load current becomes 15 A at an input signal of 12 mA.
In this case, control is disabled if the input signal exceeds 12 mA.
4 12 20
0
50
100
Input signal (mA)
Current (%)
Constant current control
Maximum load current (15 A) of heater
Control is disabled within this section.
In this case, set the gradient to 50 % so that the maximum heater load current will become 15 A at an input signal of 20 mA.
The gradient is valid even if internally set or set by the external gradient setter.
4 12 20
0
50
100
Input signal (mA)
Current (%)
Constant current control
Maximum load current (15 A) of heater
Gradient setting
50 %
7.8 Automatic Power Frequency Detection and Power Frequency Monitoring Function
Automatic power frequency detection
The instrument automatically detects a power supply frequency (50 Hz or 60 Hz) when the power is turned on.
Displays Error number 32 (Power frequency error 2) at the Error display when failed to detect Power supply frequency.
Power frequency monitoring function
This function monitors the power supply frequency and when it goes out of the detection range, the error message display
appears. Displays Error number 16 (Power frequency error 1).
To confirm power supply frequency, switch to the Power frequency monitor by pressing the Parameter key at the Error display.
(Only Power frequency monitor is available.)
Detection range: 50 Hz = 45.0 to 54.9 Hz
60 Hz = 55.0 to 64.9 Hz
Error message will be cleared when power supply frequency returns to the detection range during the operation.
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