Dual-Setpoint Controller Options
Features
- Applicable to all Micro Series digital panel meters, counters, timers
- Isolated dual-channel contact or solid state relay versions
- Form-C contact relays rated 8A at 250 Vac or 8A at 24 Vdc
- Solid state relays rated 120 mA at 125 Vac or 250 mA at 0-150 Vdc.
- Outputs derived from filtered or unfiltered signal input
- Fast response time
- Selectable output time delay
- Multiple operating modes
– output above or below setpoint
– latching or non-latching
– band deviation or hysteresis around each setpoint. - Setpoint setup via front panel pushbuttons or RS232/485
- Security lockout of front panel setpoint controls
Description
Contact Relays or Solid State
Two optional plug-in setpoint controller boards are available to add control and alarm capability to Micro DPMs, counters and remote displays:
- A board with two Form C, 8 amp, 250 Vac contact relays.
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A board with two Form A AC/DC solid state relays rated 120 mA at 125 Vac or 250 mA at 150 Vdc. The solid state version is recommended for high duty cycles and low-level loads.
Operating Modes
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Operation above or below setpoint. Each relay may be individually programmed to be energized above or below a setpoint, or may be disabled.
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Latching or non-latching. Each relay may be individually programmed to operate in a latching or non-latching mode. In the latching mode, when an alarm or shutdown condition is reached, the output remains in the alarm condition until it is reset by front panel pushbuttons, via the serial interface, or via the rear connector. In the non-latching mode, the output is automatically reset when the alarm condition no longer exists.
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Band deviation mode. Each relay may be set to operate in a band deviation mode, where an alarm is generated whenever the reading is a specified number of counts above or below the setpoint. In particular, band deviation is ideal to flag an out-of-tolerance condition.
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Hysteresis mode. Each relay may be set to operate in a hysteresis mode, where turn-on occurs at a specified amount above the setpoint and turn-off occurs at the same amount below the setpoint.
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Filtered or unfiltered input. Relay action may be derived from either the filtered or unfiltered DPM input signals. Using the unfiltered signal improves response time, which is typically 17 ms for a DPM with the solid state relay board. Fast response time is one of the major strengths of Micro DPMs, which can digitize analog data as often as 60 times per second. Using the filtered input reduces the chance of alarm triggering due to noise.
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Provisions for signal noise. A programmable time delay and reduction of relay chatter can be achieved in the DPM by selecting 1 to 128 readings in binary steps (20 ms to 2 s) prior to updating the output. Snubber circuitry is part of the contact relay board to prolong contact life. The relay response time of counters is controlled by a selectable gate time from 10 ms to 199.99 s.
Setup
Setpoint values and deviation bands are easily entered via front panel pushbuttons or by computer via the serial interface. Security lockout of the front panel pushbuttons may be set to allow operators to view but not change setpoint values. Front panel push-button operation can also be completely disabled.
The Micro Weight Meter and Batch Controller offer setpoint control modes beyond those of normal meter or counter operation.
Specifications
| Operation | |
| Power | Provided by meter. |
| Update Rate | 60 Hz or 50 Hz |
| Setup | Front panel pushbuttons or RS232/485. |
| Operating modes | Available for each output: operate above or below setpoint, latching or non-latching, band deviation mode around setpoint, hysteresis mode around setpoint, disabled. |
| Lockouts | May be set to allow display and change of setpoint by front panel pushbuttons, allow display only by alarm pushbutton, or disable pushbuttons. Setpoint compared to either filtered or unfiltered signal. |
| Input Filtering | Programmable from 1 to 128 readings. |
| Time Delay |
| Alarm Status Indication | |
| Type | Two red LED lamps |
| Lamp Lit | When relay is energized |
| Environmental | |
| Operating Temperature | 0°C to 60°C |
| Storage Temperature | -40°C to 85°C |
| Relative Humidity | 95% at 40°C, non-condensing |
| Contact Relay Version | |
| Power Rating | |
| AC Load | 8A at 250 Vac |
| DC Load | DC or 49-440 Hz |
| Isolation to Signal & Meter Ground | |
| Isolation Group | C |
| Rated Voltage | 250 Vac |
| Withstand Voltage | 4.2 kVp for 1 min |
| Response Time to Input Signal | |
| DPM Pickup Time | 26 ms typ (unfiltered) |
| DPM Release Time | 22 ms typ (unfiltered) |
| Counter Pickup or Release time | Gate time +30 ms +2 periods max |
| Solid State Relay Version | |
| Power Rating | |
| AC loads | 120 mA at 125 Vac, 20 ohms series resistance. |
| DC loads | 2 loads, 250 mA, 0-150 Vdc peak hold-off, 5 ohms series resistance. 4 loads, 120 mA, 0-150 Vdc peak hold-off, 10 ohms series resistance. |
| Isolation to Signal & Meter Ground | |
| Isolation Type | Optical |
| Safety Rating | 250 Vac, 4.2 kVp per High Voltage Test |
| Response Time to Input Signal | |
| DPM | 17 ms typ (unfiltered) |
| Counter | Gate time + 30 ms + 2 periods max |
Setpoint Operating Modes
Normal, Non-Latched Operation
In this mode, the relay closes when the reading rises above the setpoint and opens when the reading falls below the setpoint. Relay ON/OFF control action is independently programmable for each of the two relays and can be reversed through a setup command.
Latched Operation
The relay stays actuated until reset externally. This mode can be used to shut down machinery or a process when an operating limit has been exceeded, or to maintain an alarm until acknowledged by an operator when the alarm condition has passed.
Mixed Latched and Non-Latched Operation
One of the relays can operate in a non-latched mode, for instance to turn off a heater when an operating temperature setpoint is reached. The other relay can operate as a latching fail-safe backup and turn off the entire process when a second, higher setpoint is reached, indicating a malfunction.
Deviation Mode Operation
A deviation limit (50 in this example) is set up around both sides of the setpoint. The relay closes (or opens) when the reading falls within the deviation band, and opens (or closes) when the reading falls outside of this band. This mode sets up a passband around the setpoint and is often used for component testing.
Wide Hysteresis Mode Operation
In this example, a hysteresis limit of 600 is set below the setpoint. The relay closes when the reading reaches a lower limit (the setpoint less hysteresis) and opens when the reading reaches an upper limit (the setpoint).
One application is automatic tank filling. A fill operation is automatically initiated when the tank level has reached a lower level and is terminated when the level has reached an upper level.
Narrow Hysteresis Mode Operation
Hysteresis can be used to minimize the number of ON/OFF control cycles around a setpoint, thereby increasing the life of motors, relays, etc.
A very narrow hysteresis band (such as 5 counts) can also be used to minimize relay chatter around a setpoint due to electrical noise on the signal, or due to signal feedback caused by load switching. The hysteresis limit should exceed the noise amplitude.
Electrical Connections
Dual contact relays
Each load load rated 8A at 250 Vac
or 8A at 24 Vdc.
Dual contact relays
Each load load rated 8A at 250 Vac
or 8A at 24 Vdc.
Solid state, DC connection with 4 loads
Each load rated up to 120 mA at 150 Vdc,
10 ohms series resistance.
Solid state, DC connection with 2 loads
Each load rated up to 250 mA at 150 Vdc,
5 ohms series resistance.