Q. How do I determine my JEM 1 energy pulse weight or value, sometimes referred to as Ke or Pke value?
A. On the lower front of all JEM 1 meters is the meter serial plate. The meter serial plate contains a lot of information specific to the meter, including the Ke value the meter was last calibrated to at the factory. A Ke value is listed for each energy pulse output the specific meter was manufactured with, and calibrated to. The Ke value listed on the serial plate is in secondary energy measurement units, for the energy measurement function indicated. This is to say the value does not take into account the voltage and current instrument transformer ratio's the meter is connected to.
The Ke is indicated as "7.8125 Wh. This means each pulse is worth 7.8125 Watthours/pulse. Be sure to note the measurement function designation next to the Ke value(Wh = Watthour, VARh = VARhour, etc). To determine the primary value of the Watthour pulse, you would multiply 7.8125 X PT ratio X CT ratio. The resulting number is sometimes referred to as Pke. Typically, the Ke value is used to verify the pulse (which feeds to the meter's register) and meter accuracy by comparing the pulse output to a known NIST traceable reference standard. If the reference standard only accepts a 2 wire pulse input, you will need to double the meter Ke value listed to insure proper calibration of the meter. Refer to the JEM 1 Instruction Manual, Section 3, "Subassemblies, Adjustments, and Calibration" for more specific details on calibrating the JEM 1 pulse outputs.
This is a large file so we recommend that you right click on the file and save it to your computer.
JEM 1 Instruction Manual
Q. How do I determine the scaling for the JEM 1 meter's Watt or VAR 0 – 1.2mA analog outputs?
A. For the standard 120VAC, Class 10 rated meters , the meter produces 1.2mA output for the inputs listed below for 2, 2 ½ , and 3 element meters. For non-standard meters, consult the JEM 1 Instruction Manual.
2 element – 1200 Watt's or VAR's input.
2 ½ element – 2400 Watt's or VAR's input.
3 element – 1800 Watt's or VAR's input.
To determine the primary scaling of the meter when it is connected to PT and CT transformers, multiply the appropriate input listed above X PT ratio X CT ration the meter is connected to.
Q. How do you setup or program(configure) the JEM 1 register?
A. The easiest way to program the register is using the EXJSET programming software, only available through AMETEK. EXJSET is typically sold as a kit including the software, instruction manual, and communications cable. EXJSET is a DOS based program. With EXJSET, the user will specify which registers are displayed, the decimal point location for displays, a short text description to identify the register, the meters communications settings, etc. Once the user has made the necessary settings in the program, the user must save the settings before the user can configure the meter. The programming in the EXJ register can not be "read" out of the register with EXJSET. The JEM 1 meter with EXJ Register comes standard with an optical communications port on the front of the meter to facilitate programming of the meter , or local data retrieval. The EXJ Register also comes standard with RS-232 and 20mA loop communications via a 15 pin D connector on the front cover of the meter, or via connections at the rear of the meter as well. These ports can also be used for programming and data retrieval. The cable sold in the kit mates between the PC and the D connector on the meter. It is possible to issue configuration specific commands from a terminal type program on a PC, but this is not recommended if the user is inexperienced with ASCII or Binary communications protocols. Jem 1 command protocols for both the ASCII and Binary command set are available in a manual. Download the following manuals by right clicking on the file name and save it to your computer.
Q. My meter has stopped working (KYZ pulse not working, analog output not right, register stopped or won't accumulate, register display blank or corrupted, communications problems), how do I fix it?
A. General - Well, you could take the easy way out and contact AMETEK tech support. But if you can't for whatever reason, some of the JEM1 subassemblies are easily replaced by the user in the field. First, observe all safety precautions appropriate, de-energize all inputs to the meter. It is recommended to observe anti-static handling precautions when handling the JEM 1 circuit boards. Refer to the JEM 1 instruction manual for location of user replaceable subassemblies. If using spare replacement subassemblies, make sure they operate properly and are properly calibrated (where applicable) before using them to replace a defective subassembly. It is recommended that if a meter power supply board, analog, or integrator card is replaced, that the meter calibration be checked and verified before being returned to service. The first thing to check when troubleshooting any meter problem is to check the power supply voltages. Apply rated Aux power to the meter, and remove the meters front cover. Refer to the JEM 1 Instruction Manual for location of the power supply card, test point locations, and expected readings. If the power supply checks out, see below. If one of the test points is out of limits, turn off Aux power to the meter (turn off all inputs to the meter whenever removing or replacing a subassembly). Remove all the cards in the bay with the power supply (remember which slot each card was removed from) EXCEPT the power supply. Slide the EXJ register partially out of the meter, and carefully remove (pins bend easily) the connector at location J??, located at center rear of EXJ register main board. Reapply Aux power to the meter and recheck the power supply voltages at the test points. If the test point voltages are still out of limits, either the power supply board is bad, or the Aux transformer in the meter is bad. Remove Aux power, replace power supply board, and see if new power supply works. If it does, install/reconnect 1 item at a time and recheck the power supply to make sure the test points are within limits. If the installation of a card causes a power supply test point to go out of limits, the card is typically bad and needs replaced.
KYZ pulse not working (register OK) – The JEM 1 meter uses an optically isolated relay in a 6 pin IC for the pulse output ( 2 IC chips per KYZ output), these are user replaceable in the field. Refer to the JEM 1 instruction manual for the location of the IC's on the integrator card. It is recommended that both IC's be replaced if one has failed.
Analog output not correct – If there is no analog out put for the Watt of VAR output when an output is expected, typically the associated analog card for the function is bad. Refer to the JEM 1 Instruction manual for location. Replace the card, and if it corrects the problem, it is recommended the meter's calibration be rechecked before the meter is returned to service. If this is a new installation and a 2 element meter, make sure the inputs to one of the meter elements is not reversed.
Register stopped or not accumulating – If meter is producing KYZ pulses, but the register isn't accumulating, then the register is most likely bad and needs replaced. Verify the EXJ register has been properly programmed to accumulate on the correct channel, this will vary by meter model. If this is a new installation and a 2 element meter, make sure the inputs to one of the meter elements is not reversed. If you do replace the register, the replacement register will typically need reprogrammed.
Register display blank or corrupted – If the power supply is OK, typically the register is bad and needs replaced. You can attempt to reset the register to see if the register will recover. Remove the meter cover, with Aux power applied, apply a short across the 2 gold pins just to the right of the LCD display until the display reads "Reset". This should occur after about 20 seconds of shorting the pins together. Remove the short after seeing "Reset" on the display, or after 30 seconds have passed. If the register reset, it will return to a normal display. All register data and programming will be lost. A default set of register parameters will be loaded into the register if the reset is successful. The register should be reprogrammed with EXJSET before being returned to service. If the register does not display "Reset", then the register is bad and needs replaced , and the replacement register should be programmed with EXJSET before placing meter back in service.
Communications problems – It is recommended you contact tech support with questions. Replacement of the EXJ register usually solves communications failure problems in meters that were previously communicating and suddenly stopped. The replacement register will need reprogrammed with EXJSET prior to returning the meter to service.