Giraffe Incubator Service Manual June 2001
GiraffeTM Incubator Service Manual
Important The information contained in this service manual pertains only to those models of products which are marketed by Ohmeda Medical as of the effective date of this manual or the latest revision thereof. This service manual was prepared for exclusive use by Ohmeda Medical service personnel in light of their training and experience as well as the availability to them of parts, proper tools and test equipment. Consequently, Ohmeda Medical provides this service manual to its customers purely as a business convenience and for the customers general information only without warranty of the results with respect to any application of such information. Furthermore, because of the wide variety of circumstances under which maintenance and repair activities may be performed and the unique nature of each individuals own experience, capacity, and qualifications, the fact that a customer has received such information from Ohmeda Medical does not imply in anyway that Ohmeda Medical deems said individual to be qualified to perform any such maintenance or repair service. Moreover, it should not be assumed that every acceptable test and safety procedure or method, precaution, tool, equipment or device is referred to within, or that abnormal or unusual circumstances, may not warrant or suggest different or additional procedures or requirements. This manual is subject to periodic review, update and revision. Customers are cautioned to obtain and consult the latest revision before undertaking any service of the equipment. CAUTION
w Servicing of this product in accordance with this service manual should never be undertaken in the absence of proper tools, test equipment and the most recent revision to this service manual which is clearly and thoroughly understood.
This static control precaution symbol appears throughout this manual. When this symbol appears next to a procedure in this manual, static control precautions MUST be observed. Use the static control work station (Stock No. 0175-2311-000) to help ensure that static charges are safely conducted to ground and not through static sensitive devices.
Technical Competence The procedures described in this service manual should be performed by trained and authorized personnel only. Maintenance should only be undertaken by competent individuals who have a general knowledge of and experience with devices of this nature. No repairs should ever be undertaken or attempted by anyone not having such qualifications. Genuine replacement parts manufactured or sold by Ohmeda must be used for all repairs. Read completely through each step in every procedure before starting the procedure; any exceptions may result in a failure to properly and safely complete the attempted procedure.
Definitions Note: A note provides additional information to clarify a point in the text. Important: An Important statement is similar to a note, but is used for greater emphasis. CAUTION: A CAUTION statement is used when the possibility of damage to the equipment exists. WARNING: A WARNING statement is used when the possibility of injury to the patient or the operator exists.
m x y ~
Type B Electrical equipment Protective ground Functional Ground Alternating Current (AC) Static Control Precaution
Table of Contents Chapter 1 – Functional Description 1.1 Control Board ... 1-1 1.2 Relay Board ... 1-3 1.3 Display Driver Board/EL Display ... 1-3 1.4 LED Board ... 1-4 1.5 Power Supply ... 1-4 1.6 Peripheral Components ... 1-4 1.61 Rail and Heater Door Switches ... 1-4 Chapter 2- Service Checkout 2.1 Mechanical checks ... 2-1 2.2 Controller checks ... 2-2 2.3 Accessory checks ... 2-3 2.4 Cable Connections and Mechanical Controls ... 2-4 Chapter 3- Calibration 3.1 Temperature and Line Voltage Calibration ... 3-1 3.2 Humidifier calibration ... 3-3 3.3 Scale Calibration ... 3-4 3.4 Leakage Current ... 3-4 3.5 Ground Resistance ... 3-4
Chapter 4- Troubleshooting 4.1 Service Screen ... 4-1 4.2 Alarm Messages ... 4-5 4.3 Error Codes ... 4-6 4.4 Troubleshooting Table ... 4-10 4.5 Additional Troubleshooting Tips ... 4-10 Chapter 5- Repair Procedures 5.1 Hood removal for replacement ... 5-1 5.2 Uprights and End caps ... 5-2 5.3 Compartment Probe repairs ... 5-3 5.4 Lower Unit Repairs ... 5-4 5.41 Removing the chassis cover with the storage door in place ... 5-4 5.42 Incubator fan/motor/optical sensor ... 5-5 5.43 Cartridge heater replacement ... 5-5 5.44 Elevating base ... 5-6 5.45 Chassis replacement ... 5-8 5.46 Elevating footswitch ... 5-8 5.47 Humidifier heater Replacement ... 5-9 5.5 Bed Tilt Brake Shoe Replacement ... 5-10 5.6 Castor Replacement ... 5-11 5.7 Controller and Display Module repairs ... 5-11 5.71 Display module ... 5-11 5.72 Probe panel ... 5-12 5.73 Controller components ... 5-12 Chapter 6- Illustrated Parts 6.1 Exploded Views ... 6-1 6.11 Probe housing, display module and electrical enclosure ... 6-1 6.12 Bed and side doors ... 6-6 6.13 Hood and Compartment Probe ... 6-11 6.14 Chassis ... 6-12 6.15 Humidifier... 6-16 6.16 Elevating base ... 6-18 6600-0356-000
Table of Contents 6.17 Hood latch, wire covers and uprights ... 6-20 6.18 Accessory hangers ... 6-22 6.19 Storage drawer and shelves ... 6-23 6.2 Accessories ... 6-25 6.3 Labels ... 6-26 6.4 PCB layouts ... 6-29 6.5 Wiring diagrams ... 6-32 Appendix Compartment and Skin Probe Characteristics ... A-1 Specifications ... A-2
List of Figures 1-1 Block Diagram ... 1-2 2-1 Cable connections and mechanical controls ... 2-4 3-1 Control board test points ... 3-2 4-1 First service screen ... 4-1 4-2 Second service screen ... 4-2 4-3 Status menu ... 4-2 4-4 Switch diagnostic diagram ... 4-3 4-5 First service screen- diagnostics ... 4-4 5-1 Hood ... 5-1 5-2 Uprights and endcaps ... 5-2 5-3 Compartment probe ... 5-3 5-4 Bed disassembly ... 5-4 5-5 Fan motor ... 5-5 5-6 Heat sink and fan ... 5-6 5-7 Elevating base ... 5-7 5-8 Chassis bottom cover ... 5-8 5-9 Humidifier parts ... 5-9 5-10 Replacing the tilt brake ... 5-10 5-11 Display module ... 5-11 5-12 Probe panel ... 5-12 5-13 Electronics enclosure ... 5-13 6-1 Probe Panel Assembly ... 6-1 6-2 Display Module ... 6-3 6-3 Electrical enclosure ... 6-5 6-4 Bed ... 6-7 6-5 Side door (E/W) ... 6-9 6-6 Flip door, corner blocks and grommets ... 6-10 6-7 Compartment Probe ... 6-11 6-8 Upper chassis and heat sink ... 6-13 6-9 Lower chassis ... 6-15 6-10 Humidifier ... 6-17 6-11 Base and elevating column ... 6-19 6-12 Hood latch and wire covers ... 6-20 6-13 Uprights and End caps ... 6-21 6-14 Drainage hangers and DIN rail ... 6-22 6-15 Strorage Drawer ... 6-23 6-16 Instrument Shelf ... 6-24 6-17 Monitor Shelf ... 6-24 6-18 Control board ... 6-29 ii
Table of Contents 6-19 Display driver board ... 6-30 6-20 Relay board ... 6-31 6-21A Wiring Diagram Control Board ... 6-32 6-21B Wiring Diagram Elevating Base ... 6-33 6-21C Wiring Diagram Electrical Enclosure ... 6-34 6-21D Wiring Diagram Graphics Display ... 6-35 6-21E Wiring Diagram Incubator ... 6-36
wWarnings Before using the Giraffe Incubator, read through this entire manual. As with all medical equipment, attempting to use this device without a thorough understanding of its operation may result in patient or user injury. This device should only be operated by personnel trained in its operation under the direction of qualified medical personnel familiar with the risks and benefits of this type of device. Additional precautions specific to certain procedures are found in the text of this manual. Complete the “Pre-operative Checkout Procedures” section of the Operator’s manual before putting the unit into operation. If the incubator fails any portion of the checkout procedure it must be removed from use and repaired. Do not use the incubator in the presence of flammable anesthetics; an explosion hazard exists under these conditions. Always disconnect the power before performing service or maintenance procedures detailed in this manual. Apply power only if you are specifically instructed to do so as part of the procedure. Thoroughly air dry the incubator after cleaning it with flammable agents. Small amounts of flammable agents, such as ether, alcohol or similar cleaning solvents left in the incubator can cause a fire.
wCautions Only competent individuals trained in the repair of this equipment should attempt to service it as detailed in this manual. Detailed information for more extensive repairs is included in the service manual solely for the convenience of users having proper knowledge, tools and test equipment, and for service representatives trained by Ohmeda Medical.
Chapter1- Functional Description This functional description is divided into four sections representing each of the four boards. The reader should also reference the block diagram and wiring diagram when studying this section.
1.1 Control Board The Intel 80C188EC microcontroller is an enhanced X86 processor with many on-board peripheral features, such as a interrupt controller, DMA controller, peripheral chip select driver, programmable timers, etc. A programmable timer is used to control the heaters. The input to this timer is line frequency. This allows the control signal to be synchronized with the line frequency to better control the zero-crossing solid state relays. The on-board interrupt controller has several interrupts: analog-to-digital converter (ADC) conversion ready signal, overtemperature comparator output, watchdog output, power fail signal, and module interrupt signal from the system data bus. The microcontroller external bus is a multiplexed address and data bus. The system memory consists of a programmable read-only memory (PROM) and static random access memory (SRAM). The EEPROM is used for calibration values and infrequently changing variables. This memory holds the data even after power is turned off. The RS-485 integrated circuit converts the RS-232 TTL signals from the microcontroller to RS-485 signals for the bus. This bus is the main communications bus from the control board to all other boards with processors. There are two isolation transceivers used to isolate the circuits powered by +5V and the circuits powered by +5VSTBY (battery backup). The board contains a 16 channel multiplexer. There are seven temperature measurement channels. These channels measure the two patient probes with two thermistors each, the two air temperature thermistors used for display and control, and an additional thermistor used to measure the heat sink temperature. Additional channels include the humidity sensor (RHIN), LINE COMP & LINE COMP2, 5 Volts, Motor current, Vthref, VDAC, and 1.2Vind. Attached to the environmental probe connection is the relative humidity signal conditioning circuitry. The 1V reference that is used for the analog circuitry is also the maximum input voltage and the offset voltage for the ADC. This yields a purely ratiometric system. The overtemperature circuit compares the air temperature to a reference level, generates an interrupt, and turns off the heat if the air temperature is higher than the reference level. Since the thermistor measurements are digitally calibrated, the circuit must allow for various voltage levels for overtemperature thresholds. The watchdog function is housed in a RISC processor. The watchdog circuitry is independent of the 80C188 controller. The audio function is also programmed into the RISC processor. The audio circuit includes a 8752 microcontroller that reads a wavetable located in a PROM and sends the table to a digital audio circuit and amplifier. The high priority (HP) and other alarm signal lines select an output at the correct frequencies. Three OR gates are combined to generate the error signal. The inputs to the circuit are overtemperature, power failure, and system failure. This circuit generates an error signal that turns off the heater and sounds the HP alarm. This circuit is independent of the microcontroller.
Chapter 1- Functional Description
Knob Display Driver Board
Overtemp PROM Watch Dog
Future Options and Modules Power Supply
Figure 1-1 Block Diagram 1-2
Chapter1- Functional Description 1.2 Relay Board The relay board contains the circuitry to drive the three solid state relays and the safety relay circuits. The control signal for these functions is generated on the Control Board. There is a current sense circuit for the bed heater and an additional one for the humidifier heater. These circuits consist of a small signal transformer that produces a current proportional to the current through the heater circuits. The current is rectified and measured. The subsequent comparator then generates a digital level based on a specified current level. This results in a signal representing the state of the heater (on or off). The line compensation circuit consists of a signal transformer connected to the mains voltage. The secondary of this transformer feeds a full wave rectifier and a capacitor. The resulting DC voltage is proportional to mains voltage, and is measured on the control board. The line frequency circuit consists of a half wave rectifier and a comparator. This circuit generates a digital pulse synchronized with the line frequency (50 or 60 Hz). The battery backup circuitry is connected to the +12V line. The 5V regulator generates the +5V standby from either the +12V or the battery voltage, whichever is larger. If there is no mains power, 12 volts is not present, and the battery will generate the +5V standby. When 12V is present, the battery is biased out of the circuit with the diode and is merely being trickle charged. The motor driver circuit turns the DC motor coils in the incubator fan motor on and off based on feedback from the hall effect position sensors. This integrated circuit can also vary the speed, direction, and brake the motor based on input signals from the control board. The elevating base circuit consists of a series of relays that apply voltage to the elevating base motor. The ebase motor is always driven at 24-32 volts. The airflow sensor consists of an opto-coupler that outputs a clocking pulse proportional to the fan movement. The signal is AC coupled to eliminate offset voltages and drifts. The resulting pulse is half wave rectified and stored in a capacitor to yield a DC voltage proportional to the fan speed. If the fan stops or there is no fan, this DC voltage becomes zero.
1.3 Display Driver Board / EL Display The Display Driver board contains the same Intel microcontroller as the Control board. The processor on the display board is used to control the EL display contents and monitor user inputs received from the membrane switch panel and rotary encoder knob. There are two groups of digital inputs: membrane switch panel and rotary encoder knob. The membrane switches are pulled high; pressing the switch grounds the input. The encoder also has a switch, and two optically isolated lines that pulse out of phase with each other. The number of pulses represents the number of steps the knob rotates. The phase of the pulses represents the direction of the knob rotation. The display board system memory consists of a programmable read-only memory (PROM) and static random access memory (SRAM). The RS-485 integrated circuit converts the RS-232 TTL signals from the microcontroller to RS-485 signals for the bus. The timekeeping RAM has a battery integrated into the chip so that the time and date run are kept current even with the power off. The graphics controller is an S-MOS VGA controller. The graphics controller interfaces the data from the video RAM to the EL display. The controller also synchronizes the display using a horizontal pulse (LP) and a vertical pulse for the whole display frame (YD). The controller handshakes with the 80C188 using the READY line to eliminate any lost data during display refreshes. 6600-0356-000
Chapter 1- Functional Description 1.4 LED Board The LED Board contains five display banks and two display drivers. One of the display drivers controls the patient temperature and air temperature display banks. The other driver controls the patient set temperature, air set temperature, and the mode and override indicators. This allows the two large displays (patient and air temperature) to be multiplexed at a slower rate than the other LEDs. This results in brighter large displays. Each driver has a brightness potentiometer that is preset at the factory and should not be adjusted in the field.
1.5 Power Supply The universal input switching power supply converts the line voltage to +5V DC and +12V DC. This supply can source up to 75 watts. The 5 volts powers the electronics and the 12 volts is used by the EL display and for future boards.
1.6 Peripheral Components There are several peripheral components. The toroidal transformer bucks the line voltage to the range of the elevating base system. The solid state relay mounted to the chassis is used to control the bed heaters.
Chapter 2- Service Checkout WARNINGS
w Do not perform the preoperative checkout procedure while the patient occupies the unit. w Complete the preoperative checkout procedure section of this manual before putting the unit into operation. If the equipment fails any portion of the checkout procedure it must be removed from use and repaired.
2.1 Mechanical checks 1. Disconnect the power cord for the mechanical portion of the preoperative checkout procedure. 2. Examine the power cord for any signs of damage. Replace the cord if damage is evident. 3. Check that both plug retaining brackets are in place. 4. Examine the unit overall for any damaged or missing parts. 5. Check that all the casters are in firm contact with the floor and that the unit is stable. Lock the caster brakes and check that they hold the unit in place. Release the brakes and check that the unit moves smoothly. 6. Check the operation of the side doors. Open the doors and check that they swing all the way down and hang perpendicular to the bed. Check that the doors are securely attached to the unit and that the hinge pins are properly seated. Check that the inner walls are securely fastened to the doors. Close the doors and check that the latches hold the doors securely shut. The orange latch open indicators should not be visible when the latches are engaged. Check that t6he hood is in the locked position. 7. Check the tubing acces door at the top of the ventilator slot in the back wall. It should flip up easily and snap back down in place. 8. Check the portholes. Open the portholes by pressing on the latch. The cover should swing open. Close the porthole and check that the latch holds the cover securely shut and that the cover seals tightly against the porthole gasket. Check that all the porthole seals are in place and are in good condition. 9. If the unit is equipped with an iris porthole, check the iris is installed and in good condition. Check that the iris tightens when it is rotated. 10. Check that the tubing access covers in the four bed corners and the large slot grommet at the head of the bed are in place and are in good condition. 11. Check the operation of the bed. The bed should rotate easily without binding. If the bed is properly seated and locked in place, the mattress should be level. With the bed rotated back into the straight position, check to see that the bed platform extends and stops when it is pulled out on either side. Check the operation of the bed tilt mechanism. Squeeze the tilt control and push down on the foot of the bed. The head of the bed should raise easily, and should stay in position at any angle along its tilt path when the tilt control is released. Push down on the head of the bed. The foot of the bed should raise easily, and should stay in position at any angle along its tilt path when you the tilt control is released. 12. Check the operation of the hood lock. Release the lock and raise the hood. Make sure it locks in the open position. Release the lock and lower the hood. Make sure it locks in the closed position.
Chapter 2- Service Checkout 2.2 Controller checks WARNING
w Do not use the Incubator in the presence of flammable anesthetics: an explosion hazard exists under these conditions.
1. Connect the incubator power cord to a properly rated outlet . 2. Check that the compartment probe jack is plugged in at the head of the bed. 3. Connect the patient probe to jack 1 on the probe panel. 4. Switch on the power at the mains switch on the back of the unit, and at the standby switch on the jack panel, while holding in the override button (>37) during power up until the software revision screen appears. Release the button and the first service screen will appear. 5. Scroll to “Down” and select it to bring up the second service screen. Select Status to see Status screen. Check status of the software self tests. These include: incubator heater on (INCHTRON), warmer heater on (WRMHTRON), incubator/warmer heater off (I/WHTROFF), humidifier heater on (RHHTR), remote monitoring data stream (RS232LOOP), incubator fan on (FANON), and incubator fan off (FANOFF). All test should say PASS except RS232 LOOP (the connector pins must be shorted to get the PASS message). 6. Using the standby switch turn off the unit, then turn it back on. Verify the following: All the displays and indicators light The software revision appears The prompt tone begins Note: If the unit has been used in the last 2 hours, the patient history query appears. 5. Adjust the set temperature to silence the prompt tone. 6. Check the patient probe. If the probe is below 30 C, the display will show -L-. Warm it by placing it between your fingers, and verify that the baby temperature reading increases. 7. Unplug the patient probe and check that both visual and audio alarms trigger in the Baby control mode. 8. If so equipped, check the operation of the bed elevating system. Raise and lower the bed along its entire travel range, checking that the mechanism operates smoothly. Check that the pedals on both sides of the unit raise and lower the bed. 9. Check the power failure alarm and the battery backed up memory. Make note of the current control mode and temperature settings and wait one minute, then unplug the Incubator from the wall outlet. An alarm should sound and the power failure indicator should light. Wait one to two minutes and plug the Incubator back in. Verify that the alarm cancels and that the Incubator returns to the same control mode and temperature settings it displayed before the power interruption. Note: A fully charged battery should supply the power failure alarm for approximately 10 minutes. If the alarm is tested for the full 10 minutes the Incubator must be run at least two hours to recharge the battery before it is used with a patient. Total recharge time is 8 to 10 hours. 10. Perform the Leakage Current and Ground Resistance checks in Chapter 3 of this manual.
Chapter 2- Service Checkout 2.3 Accessory checks 1. Check that all accessories are securely mounted and out of the path of the hood in the open position. 2. Check the operation of any accessories with reference to their appropriate operation manuals. 3. Setup any required suction or gas supply systems. Check them for leaks as described in their respective operation manuals.
Chapter 2- Service Checkout
2.5 Cable Connections and Mechanical Controls
Numeric Temperature Displays Graphics Screen Tubing access door Control Knob
Temperature Regulation Controls
Side Door Latch
Compartment Probes Tubing Grommets Side Door Latch
RS 232 Connector
Standby Power Switch (I/O)
Humidifier Reservoir (air intake filter located behind reservoir)
Mains Power Switch
Accessory Power Outlets
Figure 2-1 Connections and controls 2-4
Power Cord Inlet
Chapter 2- Service Checkout
Control Panel Portholes Hood
Side Door Latch
Pleural Drainage Hanger
Storage Drawer Elevating Column
Bed Height Pedal
Chapter 2- Service Checkout
Chapter 3- Calibration WARNING w After performing any repair or calibration, always perform the Service Checkout Procedure before putting the unit back into service.
3.1 Temperature and line voltage calibration 1. Turn power off. 2. Remove electrical enclosure back panel. 3. Unplug the compartment sensor and patient probes from the probe panel. 4. Move jumper JP1 to the CAL MODE position on the control board (see Figure 3-1 on next page). Be sure to orient the jumper correctly so pins 5-6 and 7-8 are shorted. 5. Turn power on. After running the power-up testing INITIALIZING will be displayed and dots will move across the top of the screen. 6. After about 90 seconds CALIBRATION MODE, Enter “VREF”, and Enter “Mains” will be displayed. 7. Using a 4 ½ digit DVM (capable of measuring to 0.1 millivolt) measure VREF at TP1, pins 1 and 6 (pin 6 is ground) on the control board. Measure to the nearest 0.1 millivolt. 8. Dial in VREF using the control knob. Press the knob to enter the value. 9. Measure the Mains Voltage at the AC connectors at the bottom of the electronics enclosure cover. 10. Dial in the Mains voltage using the control knob. Press the knob to enter the value. 11. After a few seconds the dots will stop moving across the screen and DONE will appear on the top right of the display. Do not shut off the unit until the DONE message is displayed or the new calibration values will not be stored. If the message “Mains voltage calibration failed. Please enter the mains voltage again” appears this indicates the dialed in line voltage is 20% different than the measured value (not the nominal value). 12. Power down the unit and move the calibrate jumper to the NORMAL MODE position. Be sure to orient the jumper correctly so pins 1-2 and 3-4 are shorted.
Chapter 3- Calibration
Calibration jumper NORMAL MODE CAL MODE
Test Point 1
Test Point 2
Figure 3-1 Control board test points 3-2
Chapter 3- Calibration 3.2 Humidifier Calibration Important: Be sure to re-calibrate the humidifier whenever either the sensor or the control board is replaced. Important: In order for the water in the calibration bottle to be completely saturated, most of the salt should not be dissolved. There should be as little standing water above the salt line as possible to minimize the response time. The salt in the calibration bottle may only be used for a period of one year after it’s initial mix with water then the kit should be discarded. 1. Take the cap off the humidity calibration bottle and add one half cap full of distilled water to the bottle. Shake the bottle to thoroughly mix the salt and water solution. Place the elbow on the bottle. The smaller end goes over the bottle. 2. Slide the elbow over the humidity sensor (mounted on the back wall) until it stops. 3. Hold the override key while powering up to enter the service screen. 4. On the second service screen, select Cal RH. The screen will prompt “Push knob when RH reading is stable.” Wait for 20 minutes or until the RH display stabilizes (does not change by more than 1% in 5 minutes). 5. You have the option to select STABLE, SET TO DEFAULT or EXIT. STABLE initiates calibration. SET TO DEFAULT resets calibration values back to factory default settings. If you started calibration by mistake (without the calibration bottle in place, for example) you would select SET TO DEFAULT and then calibrate the unit. If you have entered the calibration routine by mistake, select EXIT to leave without initiating calibration 6. If “RH Sensor Calibration Completed.” is displayed the calibration is complete. Depress the knob to exit the Cal RH routine. 7. If “RH Sensor Calibration Failed. Try Again.” is displayed verify your setup and press the knob to try the calibration again.
Chapter 3- Calibration
3.3 Scale Calibration NOTE: The scale is calibrated using a Class F calibration weight between 1 kilogram and 8 kilograms (accuracy of 0.01%). 1. Place the test weight on the center of the bed. 2. Hold the override key (>37) while powering up to enter the service screen. 3. On the second service screen, select Cal Scale. 4. Remove the weight and push the knob at the screen prompt “REMOVE THE WEIGHT AND PUSH KNOB”. The screen will prompt “INITIALIZING...” for a few seconds. 5. Replace the weight and push the knob at the screen prompt “PLACE TEST WEIGHT AND PUSH KNOB”. The screen will prompt “MEASURING ...” for a few seconds 6. When the screen prompts “ENTER TEST WEIGHT” Dial in the test weight to the nearest gram. Press the knob to enter. The screen will prompt “CALCULATING.” for a few seconds. 7. When the screen prompts: SAVE AND EXIT EXIT ONLY RESTORE DEFAULT Select and enter “SAVE AND EXIT” 8. Turn off the power to exit the service mode.
3.4 Leakage Current Use approved equipment and techniques to test the unit’s leakage current and ground continuity. Follow the directions supplied by the test equipment manufacturer to verify the following: 1. Less than 100 microamperes measured at any exposed metal surface for equipment rated at 120 Vac, 50/ 60 Hz. 2. Less than 200 microamperes measured at any exposed metal surface for equipment rated at 220 Vac, 50/ 60 Hz or 240 Vac, 50/60 Hz.
3.5 Ground Resistance Check Use a electrical safety analyzer to measure the resistance between the ground pin on the line cord plug and exposed metal of the electronic enclosure. The ground resistance must be less than 0.1 ohms.